I post this (if I understand the question from title and text: single letter addition anywhere in string) to illustrate how unwieldy the graph gets just 3 levels deep. Here just starting with "a".
fun[x_] := With[{c = Characters[x]},
Thread[x ->
Select[
DictionaryLookup[
StringExpression @@ Riffle[c, ___, {1, 2 Length@c + 1, 2}]],
StringLength@# == StringLength@x + 1 &]]]
Building graph from "a", just for 3 iterations:
gr = NestList[Join @@ fun /@Union[ #[[All, 2]]] &, fun["a"], 3];
Visualizing:
Graph[Join @@ gr]

This would be unwieldy to label/interpret without much cleverer ways to cone down on or render interactive (I look forward to approaches):
The edges for just 2 interations(!):
{"a" -> "ad", "a" -> "ah", "a" -> "am", "a" -> "an", "a" -> "as",
"a" -> "at", "a" -> "ax", "a" -> "fa", "a" -> "ha", "a" -> "la",
"a" -> "ma", "a" -> "pa", "a" -> "ta", "a" -> "ya", "ad" -> "add",
"ad" -> "ado", "ad" -> "ads", "ad" -> "adz", "ad" -> "aid",
"ad" -> "and", "ad" -> "bad", "ad" -> "cad", "ad" -> "dad",
"ad" -> "fad", "ad" -> "gad", "ad" -> "had", "ad" -> "lad",
"ad" -> "mad", "ad" -> "pad", "ad" -> "sad", "ad" -> "tad",
"ad" -> "Tad", "ad" -> "wad", "ah" -> "aah", "ah" -> "aha",
"ah" -> "ash", "ah" -> "bah", "ah" -> "nah", "ah" -> "pah",
"ah" -> "rah", "am" -> "aim", "am" -> "amp", "am" -> "arm",
"am" -> "cam", "am" -> "Cam", "am" -> "dam", "am" -> "ham",
"am" -> "Ham", "am" -> "jam", "am" -> "lam", "am" -> "mam",
"am" -> "Nam", "am" -> "Pam", "am" -> "ram", "am" -> "Sam",
"am" -> "tam", "am" -> "yam", "an" -> "and", "an" -> "ans",
"an" -> "ant", "an" -> "any", "an" -> "awn", "an" -> "ban",
"an" -> "can", "an" -> "Dan", "an" -> "fan", "an" -> "Han",
"an" -> "Ian", "an" -> "Jan", "an" -> "Kan", "an" -> "man",
"an" -> "Man", "an" -> "nan", "an" -> "Nan", "an" -> "pan",
"an" -> "Pan", "an" -> "ran", "an" -> "San", "an" -> "tan",
"an" -> "van", "an" -> "Van", "an" -> "wan", "as" -> "abs",
"as" -> "ads", "as" -> "ans", "as" -> "ash", "as" -> "ask",
"as" -> "asp", "as" -> "ass", "as" -> "gas", "as" -> "has",
"as" -> "mas", "as" -> "pas", "as" -> "was", "at" -> "act",
"at" -> "aft", "at" -> "ant", "at" -> "apt", "at" -> "art",
"at" -> "ate", "at" -> "bat", "at" -> "cat", "at" -> "eat",
"at" -> "fat", "at" -> "hat", "at" -> "mat", "at" -> "Nat",
"at" -> "oat", "at" -> "pat", "at" -> "Pat", "at" -> "rat",
"at" -> "sat", "at" -> "tat", "at" -> "vat", "ax" -> "axe",
"ax" -> "fax", "ax" -> "lax", "ax" -> "Max", "ax" -> "sax",
"ax" -> "Sax", "ax" -> "tax", "ax" -> "wax", "fa" -> "fab",
"fa" -> "fad", "fa" -> "fag", "fa" -> "fan", "fa" -> "far",
"fa" -> "fat", "fa" -> "fax", "fa" -> "fay", "fa" -> "Ufa",
"ha" -> "aha", "ha" -> "had", "ha" -> "hag", "ha" -> "haj",
"ha" -> "ham", "ha" -> "hap", "ha" -> "has", "ha" -> "hat",
"ha" -> "haw", "ha" -> "hay", "la" -> "Ila", "la" -> "lab",
"la" -> "lac", "la" -> "lad", "la" -> "lag", "la" -> "lam",
"la" -> "lap", "la" -> "lav", "la" -> "law", "la" -> "lax",
"la" -> "lay", "la" -> "lea", "la" -> "Ola", "ma" -> "mac",
"ma" -> "mad", "ma" -> "mam", "ma" -> "man", "ma" -> "map",
"ma" -> "mar", "ma" -> "mas", "ma" -> "mat", "ma" -> "maw",
"ma" -> "may", "pa" -> "pad", "pa" -> "pah", "pa" -> "pal",
"pa" -> "pan", "pa" -> "pap", "pa" -> "par", "pa" -> "pas",
"pa" -> "pat", "pa" -> "paw", "pa" -> "pay", "pa" -> "pea",
"pa" -> "spa", "ta" -> "eta", "ta" -> "tab", "ta" -> "tad",
"ta" -> "tag", "ta" -> "tam", "ta" -> "tan", "ta" -> "tap",
"ta" -> "tar", "ta" -> "tat", "ta" -> "tau", "ta" -> "tax",
"ta" -> "tea", "ya" -> "yak", "ya" -> "yam", "ya" -> "yap",
"ya" -> "yaw", "ya" -> "yea", "add" -> "adds", "ado" -> "dado",
"ads" -> "adds", "ads" -> "aids", "ads" -> "ands", "ads" -> "cads",
"ads" -> "dads", "ads" -> "fads", "ads" -> "gads", "ads" -> "lads",
"ads" -> "pads", "ads" -> "rads", "ads" -> "tads", "ads" -> "wads",
"aid" -> "acid", "aid" -> "aide", "aid" -> "aids", "aid" -> "amid",
"aid" -> "arid", "aid" -> "avid", "aid" -> "laid", "aid" -> "maid",
"aid" -> "paid", "aid" -> "raid", "aid" -> "said", "and" -> "ands",
"and" -> "band", "and" -> "hand", "and" -> "land", "and" -> "Land",
"and" -> "rand", "and" -> "Rand", "and" -> "sand", "and" -> "Sand",
"and" -> "wand", "bad" -> "bade", "bad" -> "bald", "bad" -> "band",
"bad" -> "bard", "bad" -> "baud", "bad" -> "bawd", "bad" -> "bead",
"bad" -> "brad", "cad" -> "cads", "cad" -> "card", "cad" -> "clad",
"cad" -> "scad", "dad" -> "dado", "dad" -> "dads", "dad" -> "dead",
"dad" -> "dyad", "fad" -> "fade", "fad" -> "fads", "gad" -> "egad",
"gad" -> "gads", "gad" -> "gawd", "gad" -> "glad", "gad" -> "goad",
"gad" -> "grad", "had" -> "Chad", "had" -> "hand", "had" -> "hard",
"had" -> "head", "had" -> "shad", "had" -> "Thad", "lad" -> "clad",
"lad" -> "glad", "lad" -> "lade", "lad" -> "lads", "lad" -> "lady",
"lad" -> "laid", "lad" -> "land", "lad" -> "lard", "lad" -> "laud",
"lad" -> "lead", "lad" -> "load", "lad" -> "Vlad", "mad" -> "made",
"mad" -> "maid", "mad" -> "mead", "pad" -> "pads", "pad" -> "paid",
"sad" -> "said", "sad" -> "sand", "sad" -> "scad", "sad" -> "shad",
"tad" -> "tads", "tad" -> "toad", "tad" -> "trad", "Tad" -> "Thad",
"wad" -> "wade", "wad" -> "wadi", "wad" -> "wads", "wad" -> "wand",
"wad" -> "ward", "wad" -> "woad", "aah" -> "ayah", "aha" -> "ahas",
"ash" -> "ashy", "ash" -> "bash", "ash" -> "cash", "ash" -> "Cash",
"ash" -> "dash", "ash" -> "gash", "ash" -> "hash", "ash" -> "lash",
"ash" -> "mash", "ash" -> "Nash", "ash" -> "rash", "ash" -> "sash",
"ash" -> "wash", "ash" -> "Wash", "bah" -> "bahs", "bah" -> "baht",
"bah" -> "bash", "bah" -> "bath", "bah" -> "blah", "pah" -> "path",
"rah" -> "rahs", "rah" -> "rash", "aim" -> "aims", "aim" -> "maim",
"amp" -> "amps", "amp" -> "camp", "amp" -> "damp", "amp" -> "lamp",
"amp" -> "ramp", "amp" -> "tamp", "amp" -> "vamp", "arm" -> "arms",
"arm" -> "army", "arm" -> "arum", "arm" -> "farm", "arm" -> "harm",
"arm" -> "warm", "cam" -> "calm", "cam" -> "came", "cam" -> "camp",
"cam" -> "cams", "cam" -> "clam", "cam" -> "cram", "cam" -> "scam",
"dam" -> "Adam", "dam" -> "dame", "dam" -> "damn", "dam" -> "damp",
"dam" -> "dams", "dam" -> "dram", "dam" -> "Edam", "ham" -> "hams",
"ham" -> "harm", "ham" -> "sham", "ham" -> "wham", "jam" -> "jamb",
"jam" -> "jams", "lam" -> "clam", "lam" -> "Elam", "lam" -> "flam",
"lam" -> "glam", "lam" -> "lama", "lam" -> "lamb", "lam" -> "lame",
"lam" -> "lamp", "lam" -> "lams", "lam" -> "loam", "lam" -> "slam",
"mam" -> "imam", "mam" -> "maim", "mam" -> "mama", "mam" -> "mams",
"ram" -> "cram", "ram" -> "dram", "ram" -> "gram", "ram" -> "pram",
"ram" -> "ramp", "ram" -> "rams", "ram" -> "ream", "ram" -> "roam",
"ram" -> "tram", "Sam" -> "Siam", "Sam" -> "Spam", "tam" -> "tame",
"tam" -> "tamp", "tam" -> "tams", "tam" -> "team", "tam" -> "tram",
"yam" -> "yams", "and" -> "ands", "and" -> "band", "and" -> "hand",
"and" -> "land", "and" -> "Land", "and" -> "rand", "and" -> "Rand",
"and" -> "sand", "and" -> "Sand", "and" -> "wand", "ans" -> "ands",
"ans" -> "ants", "ans" -> "anus", "ans" -> "awns", "ans" -> "bans",
"ans" -> "cans", "ans" -> "Dans", "ans" -> "fans", "ans" -> "Hans",
"ans" -> "Kans", "ans" -> "mans", "ans" -> "nans", "ans" -> "pans",
"ans" -> "sans", "ans" -> "tans", "ans" -> "vans", "ant" -> "ante",
"ant" -> "anti", "ant" -> "ants", "ant" -> "aunt", "ant" -> "cant",
"ant" -> "Kant", "ant" -> "pant", "ant" -> "rant", "ant" -> "want",
"any" -> "many", "any" -> "zany", "awn" -> "awns", "awn" -> "dawn",
"awn" -> "Dawn", "awn" -> "fawn", "awn" -> "lawn", "awn" -> "pawn",
"awn" -> "yawn", "ban" -> "band", "ban" -> "bane", "ban" -> "bang",
"ban" -> "bani", "ban" -> "bank", "ban" -> "bans", "ban" -> "barn",
"ban" -> "bean", "ban" -> "bran", "can" -> "cane", "can" -> "cans",
"can" -> "cant", "can" -> "clan", "can" -> "cyan", "can" -> "scan",
"can" -> "Scan", "Dan" -> "Dana", "Dan" -> "Dane", "Dan" -> "Dans",
"Dan" -> "Dawn", "Dan" -> "Dean", "fan" -> "fain", "fan" -> "fang",
"fan" -> "fans", "fan" -> "faun", "fan" -> "fawn", "fan" -> "flan",
"Han" -> "Hahn", "Han" -> "Hank", "Han" -> "Hans", "Ian" -> "Iran",
"Ian" -> "Ivan", "Jan" -> "Jain", "Jan" -> "Jana", "Jan" -> "Jane",
"Jan" -> "Jean", "Jan" -> "Joan", "Jan" -> "Juan", "Kan" -> "Kane",
"Kan" -> "Kano", "Kan" -> "Kans", "Kan" -> "Kant", "Kan" -> "Kean",
"Kan" -> "Khan", "Kan" -> "Klan", "man" -> "main", "man" -> "mane",
"man" -> "mans", "man" -> "many", "man" -> "mean", "man" -> "moan",
"man" -> "Oman", "Man" -> "Mani", "Man" -> "Mann", "Man" -> "Manx",
"nan" -> "nans", "pan" -> "pain", "pan" -> "pane", "pan" -> "pang",
"pan" -> "pans", "pan" -> "pant", "pan" -> "pawn", "pan" -> "plan",
"pan" -> "span", "pan" -> "Span", "ran" -> "bran", "ran" -> "Bran",
"ran" -> "Fran", "ran" -> "gran", "ran" -> "Iran", "ran" -> "Oran",
"ran" -> "rain", "ran" -> "rand", "ran" -> "rang", "ran" -> "rank",
"ran" -> "rant", "ran" -> "roan", "ran" -> "Tran", "San" -> "Sana",
"San" -> "Sand", "San" -> "Sang", "San" -> "Scan", "San" -> "Sean",
"San" -> "Span", "San" -> "Stan", "tan" -> "Stan", "tan" -> "tang",
"tan" -> "tank", "tan" -> "tans", "tan" -> "tarn", "tan" -> "than",
"van" -> "Evan", "van" -> "Ivan", "van" -> "vain", "van" -> "vane",
"van" -> "vans", "Van" -> "Vang", "wan" -> "swan", "wan" -> "wain",
"wan" -> "wand", "wan" -> "wane", "wan" -> "wank", "wan" -> "want",
"wan" -> "warn", "wan" -> "wean", "abs" -> "albs", "abs" -> "cabs",
"abs" -> "dabs", "abs" -> "gabs", "abs" -> "jabs", "abs" -> "labs",
"abs" -> "Labs", "abs" -> "nabs", "abs" -> "tabs", "ads" -> "adds",
"ads" -> "aids", "ads" -> "ands", "ads" -> "cads", "ads" -> "dads",
"ads" -> "fads", "ads" -> "gads", "ads" -> "lads", "ads" -> "pads",
"ads" -> "rads", "ads" -> "tads", "ads" -> "wads", "ans" -> "ands",
"ans" -> "ants", "ans" -> "anus", "ans" -> "awns", "ans" -> "bans",
"ans" -> "cans", "ans" -> "Dans", "ans" -> "fans", "ans" -> "Hans",
"ans" -> "Kans", "ans" -> "mans", "ans" -> "nans", "ans" -> "pans",
"ans" -> "sans", "ans" -> "tans", "ans" -> "vans", "ash" -> "ashy",
"ash" -> "bash", "ash" -> "cash", "ash" -> "Cash", "ash" -> "dash",
"ash" -> "gash", "ash" -> "hash", "ash" -> "lash", "ash" -> "mash",
"ash" -> "Nash", "ash" -> "rash", "ash" -> "sash", "ash" -> "wash",
"ash" -> "Wash", "ask" -> "asks", "ask" -> "bask", "ask" -> "cask",
"ask" -> "mask", "ask" -> "Sask", "ask" -> "task", "asp" -> "asap",
"asp" -> "asps", "asp" -> "gasp", "asp" -> "hasp", "asp" -> "rasp",
"asp" -> "wasp", "ass" -> "asks", "ass" -> "asps", "ass" -> "bass",
"ass" -> "Bass", "ass" -> "Kass", "ass" -> "lass", "ass" -> "mass",
"ass" -> "pass", "ass" -> "sass", "ass" -> "Tass", "gas" -> "gabs",
"gas" -> "gads", "gas" -> "gags", "gas" -> "gals", "gas" -> "gaps",
"gas" -> "gars", "gas" -> "gash", "gas" -> "gasp", "gas" -> "gays",
"has" -> "ahas", "has" -> "hags", "has" -> "hams", "has" -> "hash",
"has" -> "hasp", "has" -> "hast", "has" -> "hats", "has" -> "haws",
"has" -> "hays", "mas" -> "macs", "mas" -> "mags", "mas" -> "mams",
"mas" -> "mans", "mas" -> "maps", "mas" -> "mars", "mas" -> "mash",
"mas" -> "mask", "mas" -> "mass", "mas" -> "mast", "mas" -> "mats",
"mas" -> "maws", "mas" -> "Xmas", "pas" -> "pads", "pas" -> "pals",
"pas" -> "pans", "pas" -> "paps", "pas" -> "pars", "pas" -> "pass",
"pas" -> "past", "pas" -> "pats", "pas" -> "paws", "pas" -> "pays",
"pas" -> "peas", "pas" -> "spas", "was" -> "twas", "was" -> "wads",
"was" -> "wags", "was" -> "wars", "was" -> "wash", "was" -> "wasp",
"was" -> "wast", "was" -> "ways", "act" -> "acts", "act" -> "fact",
"act" -> "pact", "act" -> "tact", "aft" -> "daft", "aft" -> "haft",
"aft" -> "raft", "aft" -> "Taft", "aft" -> "waft", "ant" -> "ante",
"ant" -> "anti", "ant" -> "ants", "ant" -> "aunt", "ant" -> "cant",
"ant" -> "Kant", "ant" -> "pant", "ant" -> "rant", "ant" -> "want",
"apt" -> "rapt", "art" -> "arts", "art" -> "arty", "art" -> "Bart",
"art" -> "cart", "art" -> "dart", "art" -> "hart", "art" -> "Hart",
"art" -> "kart", "art" -> "mart", "art" -> "part", "art" -> "tart",
"art" -> "wart", "ate" -> "ante", "ate" -> "ates", "ate" -> "bate",
"ate" -> "date", "ate" -> "fate", "ate" -> "gate", "ate" -> "hate",
"ate" -> "Kate", "ate" -> "late", "ate" -> "mate", "ate" -> "Nate",
"ate" -> "pate", "ate" -> "Pate", "ate" -> "rate", "ate" -> "sate",
"ate" -> "Tate", "bat" -> "baht", "bat" -> "bait", "bat" -> "bast",
"bat" -> "bate", "bat" -> "bath", "bat" -> "bats", "bat" -> "beat",
"bat" -> "boat", "bat" -> "brat", "cat" -> "cant", "cat" -> "cart",
"cat" -> "cast", "cat" -> "cats", "cat" -> "chat", "cat" -> "coat",
"cat" -> "scat", "eat" -> "beat", "eat" -> "east", "eat" -> "eats",
"eat" -> "feat", "eat" -> "heat", "eat" -> "meat", "eat" -> "neat",
"eat" -> "peat", "eat" -> "seat", "eat" -> "teat", "fat" -> "fact",
"fat" -> "fast", "fat" -> "fate", "fat" -> "fats", "fat" -> "feat",
"fat" -> "fiat", "fat" -> "flat", "fat" -> "frat", "hat" -> "chat",
"hat" -> "ghat", "hat" -> "haft", "hat" -> "halt", "hat" -> "hart",
"hat" -> "hast", "hat" -> "hate", "hat" -> "hath", "hat" -> "hats",
"hat" -> "heat", "hat" -> "phat", "hat" -> "shat", "hat" -> "that",
"hat" -> "what", "mat" -> "malt", "mat" -> "mart", "mat" -> "mast",
"mat" -> "mate", "mat" -> "math", "mat" -> "mats", "mat" -> "meat",
"mat" -> "moat", "Nat" -> "Nate", "oat" -> "boat", "oat" -> "coat",
"oat" -> "goat", "oat" -> "moat", "oat" -> "oath", "oat" -> "oats",
"pat" -> "pact", "pat" -> "pant", "pat" -> "part", "pat" -> "past",
"pat" -> "pate", "pat" -> "path", "pat" -> "pats", "pat" -> "peat",
"pat" -> "phat", "pat" -> "prat", "pat" -> "spat", "Pat" -> "Pate",
"rat" -> "brat", "rat" -> "drat", "rat" -> "frat", "rat" -> "prat",
"rat" -> "raft", "rat" -> "rant", "rat" -> "rapt", "rat" -> "rate",
"rat" -> "rats", "sat" -> "salt", "sat" -> "sate", "sat" -> "scat",
"sat" -> "seat", "sat" -> "shat", "sat" -> "slat", "sat" -> "spat",
"sat" -> "swat", "tat" -> "tact", "tat" -> "tart", "tat" -> "tats",
"tat" -> "taut", "tat" -> "teat", "tat" -> "that", "vat" -> "vast",
"vat" -> "vats", "axe" -> "axed", "axe" -> "axes", "axe" -> "axle",
"fax" -> "flax", "lax" -> "flax", "Max" -> "Manx", "Max" -> "Marx",
"tax" -> "taxi", "wax" -> "waxy", "fab" -> "flab", "fad" -> "fade",
"fad" -> "fads", "fag" -> "fags", "fag" -> "fang", "fag" -> "flag",
"fan" -> "fain", "fan" -> "fang", "fan" -> "fans", "fan" -> "faun",
"fan" -> "fawn", "fan" -> "flan", "far" -> "afar", "far" -> "fair",
"far" -> "fare", "far" -> "farm", "far" -> "faro", "far" -> "fear",
"fat" -> "fact", "fat" -> "fast", "fat" -> "fate", "fat" -> "fats",
"fat" -> "feat", "fat" -> "fiat", "fat" -> "flat", "fat" -> "frat",
"fax" -> "flax", "fay" -> "fays", "fay" -> "flay", "fay" -> "fray",
"aha" -> "ahas", "had" -> "Chad", "had" -> "hand", "had" -> "hard",
"had" -> "head", "had" -> "shad", "had" -> "Thad", "hag" -> "hags",
"hag" -> "hang", "hag" -> "shag", "haj" -> "hajj", "ham" -> "hams",
"ham" -> "harm", "ham" -> "sham", "ham" -> "wham", "hap" -> "chap",
"hap" -> "harp", "hap" -> "hasp", "hap" -> "heap", "has" -> "ahas",
"has" -> "hags", "has" -> "hams", "has" -> "hash", "has" -> "hasp",
"has" -> "hast", "has" -> "hats", "has" -> "haws", "has" -> "hays",
"hat" -> "chat", "hat" -> "ghat", "hat" -> "haft", "hat" -> "halt",
"hat" -> "hart", "hat" -> "hast", "hat" -> "hate", "hat" -> "hath",
"hat" -> "hats", "hat" -> "heat", "hat" -> "phat", "hat" -> "shat",
"hat" -> "that", "hat" -> "what", "haw" -> "hawk", "haw" -> "haws",
"haw" -> "Shaw", "haw" -> "thaw", "hay" -> "hays", "hay" -> "hazy",
"hay" -> "shay", "lab" -> "blab", "lab" -> "flab", "lab" -> "labs",
"lab" -> "lamb", "lab" -> "slab", "lac" -> "lace", "lac" -> "lack",
"lac" -> "lacs", "lac" -> "lacy", "lad" -> "clad", "lad" -> "glad",
"lad" -> "lade", "lad" -> "lads", "lad" -> "lady", "lad" -> "laid",
"lad" -> "land", "lad" -> "lard", "lad" -> "laud", "lad" -> "lead",
"lad" -> "load", "lad" -> "Vlad", "lag" -> "blag", "lag" -> "flag",
"lag" -> "lags", "lag" -> "slag", "lam" -> "clam", "lam" -> "Elam",
"lam" -> "flam", "lam" -> "glam", "lam" -> "lama", "lam" -> "lamb",
"lam" -> "lame", "lam" -> "lamp", "lam" -> "lams", "lam" -> "loam",
"lam" -> "slam", "lap" -> "clap", "lap" -> "flap", "lap" -> "lamp",
"lap" -> "laps", "lap" -> "leap", "lap" -> "slap", "lav" -> "lava",
"lav" -> "lave", "lav" -> "lavs", "lav" -> "Olav", "lav" -> "Slav",
"law" -> "claw", "law" -> "flaw", "law" -> "lawn", "law" -> "laws",
"law" -> "slaw", "lax" -> "flax", "lay" -> "clay", "lay" -> "Clay",
"lay" -> "flay", "lay" -> "lacy", "lay" -> "lady", "lay" -> "lays",
"lay" -> "lazy", "lay" -> "play", "lay" -> "slay", "lea" -> "flea",
"lea" -> "ilea", "lea" -> "lead", "lea" -> "leaf", "lea" -> "leak",
"lea" -> "lean", "lea" -> "leap", "lea" -> "leas", "lea" -> "plea",
"Ola" -> "Olaf", "Ola" -> "Olav", "Ola" -> "Olga", "mac" -> "mace",
"mac" -> "mack", "mac" -> "macs", "mad" -> "made", "mad" -> "maid",
"mad" -> "mead", "mam" -> "imam", "mam" -> "maim", "mam" -> "mama",
"mam" -> "mams", "man" -> "main", "man" -> "mane", "man" -> "mans",
"man" -> "many", "man" -> "mean", "man" -> "moan", "man" -> "Oman",
"map" -> "maps", "mar" -> "mare", "mar" -> "mark", "mar" -> "marl",
"mar" -> "mars", "mar" -> "mart", "mar" -> "Omar", "mas" -> "macs",
"mas" -> "mags", "mas" -> "mams", "mas" -> "mans", "mas" -> "maps",
"mas" -> "mars", "mas" -> "mash", "mas" -> "mask", "mas" -> "mass",
"mas" -> "mast", "mas" -> "mats", "mas" -> "maws", "mas" -> "Xmas",
"mat" -> "malt", "mat" -> "mart", "mat" -> "mast", "mat" -> "mate",
"mat" -> "math", "mat" -> "mats", "mat" -> "meat", "mat" -> "moat",
"maw" -> "maws", "may" -> "many", "may" -> "mayo", "pad" -> "pads",
"pad" -> "paid", "pah" -> "path", "pal" -> "opal", "pal" -> "Opal",
"pal" -> "pail", "pal" -> "pale", "pal" -> "pall", "pal" -> "palm",
"pal" -> "pals", "pal" -> "pawl", "pal" -> "peal", "pan" -> "pain",
"pan" -> "pane", "pan" -> "pang", "pan" -> "pans", "pan" -> "pant",
"pan" -> "pawn", "pan" -> "plan", "pan" -> "span", "pan" -> "Span",
"pap" -> "papa", "pap" -> "paps", "par" -> "pair", "par" -> "para",
"par" -> "pare", "par" -> "park", "par" -> "pars", "par" -> "part",
"par" -> "pear", "par" -> "spar", "pas" -> "pads", "pas" -> "pals",
"pas" -> "pans", "pas" -> "paps", "pas" -> "pars", "pas" -> "pass",
"pas" -> "past", "pas" -> "pats", "pas" -> "paws", "pas" -> "pays",
"pas" -> "peas", "pas" -> "spas", "pat" -> "pact", "pat" -> "pant",
"pat" -> "part", "pat" -> "past", "pat" -> "pate", "pat" -> "path",
"pat" -> "pats", "pat" -> "peat", "pat" -> "phat", "pat" -> "prat",
"pat" -> "spat", "paw" -> "pawl", "paw" -> "pawn", "paw" -> "paws",
"pay" -> "pacy", "pay" -> "pays", "pay" -> "play", "pay" -> "pray",
"pay" -> "spay", "pea" -> "peak", "pea" -> "peal", "pea" -> "pear",
"pea" -> "peas", "pea" -> "peat", "pea" -> "plea", "spa" -> "spam",
"spa" -> "span", "spa" -> "spar", "spa" -> "spas", "spa" -> "spat",
"spa" -> "spay", "eta" -> "beta", "eta" -> "etas", "eta" -> "feta",
"eta" -> "Leta", "eta" -> "Meta", "eta" -> "zeta", "tab" -> "stab",
"tab" -> "tabs", "tad" -> "tads", "tad" -> "toad", "tad" -> "trad",
"tag" -> "stag", "tag" -> "tags", "tag" -> "tang", "tam" -> "tame",
"tam" -> "tamp", "tam" -> "tams", "tam" -> "team", "tam" -> "tram",
"tan" -> "Stan", "tan" -> "tang", "tan" -> "tank", "tan" -> "tans",
"tan" -> "tarn", "tan" -> "than", "tap" -> "tamp", "tap" -> "tape",
"tap" -> "taps", "tap" -> "tarp", "tap" -> "trap", "tar" -> "star",
"tar" -> "tare", "tar" -> "tarn", "tar" -> "taro", "tar" -> "tarp",
"tar" -> "tars", "tar" -> "tart", "tar" -> "tear", "tat" -> "tact",
"tat" -> "tart", "tat" -> "tats", "tat" -> "taut", "tat" -> "teat",
"tat" -> "that", "tau" -> "taus", "tau" -> "taut", "tax" -> "taxi",
"tea" -> "teak", "tea" -> "teal", "tea" -> "team", "tea" -> "tear",
"tea" -> "teas", "tea" -> "teat", "yak" -> "yaks", "yak" -> "yank",
"yam" -> "yams", "yap" -> "yaps", "yaw" -> "yawl", "yaw" -> "yawn",
"yaw" -> "yaws", "yea" -> "yeah", "yea" -> "year", "yea" -> "yeas"}
UPDATE
Just for fun (and using kguler's beautiful styling) for the "root" "a":
g[u_, n_] := NestList[Join @@ fun /@ Union[#[[All, 2]]] &, fun[u], n];
st[t_, l_] := {GraphLayout -> {"RadialEmbedding", "RootVertex" -> t},
VertexStyle -> {_ :> White, (x_ /; StringLength[x] == l) ->
Directive[{Red, PointSize[.01]}],
t -> Directive[{Blue, PointSize[.01]}]},
VertexLabels -> {Placed["Name",
Tooltip], (x_ /; StringLength[x] == l) ->
Placed[Style[x, Red, 12], {Tooltip, Before}]},
VertexShapeFunction -> "Point", LabelStyle -> Red,
ImageSize -> 700,
EdgeStyle -> Directive[Opacity[.5], Hue[.15, .5, .8]],
Background -> Black, EdgeShapeFunction -> (Line[#1] &)};
With[{bas = g["a", 7]}, Manipulate[
ve = Prepend[
Through[{VertexCount, EdgeCount}[
Graph[Join @@ bas[[1 ;; #]]]]] & /@ Range[8], {1, 0}];
Column[{
Row[{
ListPlot[Transpose[ve], Joined -> True, Frame -> True,
PlotLegends -> {"Vertex Count", "EdgeCount"},
FrameLabel -> {"Base string length", "Count"},
ImageSize -> 250],
ListPlot[Transpose[Differences@(ve)], Joined -> True,
Frame -> True, PlotLegends -> {"Vertex Count", "EdgeCount"},
FrameLabel -> {"Base string length", "Change"},
ImageSize -> 250]}],
grp = Graph[Join @@ bas[[1 ;; s]], st["a", s + 1]]
}],
{s, Range[8]}]]
