list = Symbol /@ CharacterRange["a", "n"];
MapAt[Style[#, Red] &, list, List /@ {4, 9, 2}];
MapAt[Style[#, Green] &, %, List /@ {3, 5, 7}];
MapAt[Style[#, Blue] &, %, List /@ {8, 1, 6}]
I am sure there is a better way do this, could you give any better ideas?