One vertex per element, one color per generator, with an edge from x to x·s.
(1,2) involution — undirected(3,4,6,12,7,13,20,33,8,14,21,34,22,35,44,56,9,11,19,29,23,30,42,51,24,31,43,52,45,53,61,64)(5,10,16,25,17,27,39,46,18,28,40,47,41,50,60,62,15,26,36,32,37,48,57,54,38,49,58,55,59,63,66,65)(3,5)(4,10,11,26)(6,16)(7,17)(8,18)(9,15)(12,32,29,25)(13,27,30,48)(14,28,31,49)(19,36)(20,39)(21,40)(22,41)(23,37)(24,38)(33,54,51,46)(34,55,52,47)(35,50,53,63)(42,57)(43,58)(44,60)(45,59)(56,65,64,62)(61,66)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.