Automatically color vertices by name in a large network

Question

The following code produces a graph with vertices N1, N2, and Nw colored yellow, and vertices Fx, Fz, F3, F4 and F5 colored red. For this, I used VertexStyle. However, separately listing each vertex in VertexStyle is not efficient for a graph with thousands of N and F vertices.

Is there an automated way to color vertices by the first letter in their name, i.e. the "N" and the "F"?

edges = {N1 -> N2, N2 -> Nw, Fx -> N3, Fx -> F4, N1 -> F4, N1 -> Fz, 
   N2 -> F3, N2 -> F4, F3 -> F4, F4 -> F5};
Graph[
 edges, 
 GraphLayout -> {"LayeredDigraphEmbedding", "Orientation" -> Left}, 
 VertexLabels -> Placed["Name", Center], VertexSize -> 0.35, 
 VertexStyle -> 
  {Fx | Fz | F3 | F4 | F5 -> Red, 
   N1 | N2 | Nw -> Yellow}
]

Answer 1

You can use patterns in VertexStyle:

VertexStyle ->
 {
   _?(StringPart[SymbolName[#], 1] === "N" &) -> Yellow,
   _?(StringPart[SymbolName[#], 1] === "F" &) -> Red
 }

So your code would become:

edges = {N1 -> N2, N2 -> Nw, Fx -> N3, Fx -> F4, N1 -> F4, 
         N1 -> Fz, N2 -> F3, N2 -> F4, F3 -> F4, F4 -> F5};

Graph[edges, 
  GraphLayout -> {"LayeredDigraphEmbedding", "Orientation" -> Left}, 
  VertexLabels -> Placed["Name", Center], VertexSize -> 0.35, 
  VertexStyle ->
  {
    _?(StringPart[SymbolName[#], 1] === "N" &) -> Yellow,
    _?(StringPart[SymbolName[#], 1] === "F" &) -> Red
  }
]