One vertex per element, one color per generator, with an edge from x to x·s.
(1,2) involution — undirected(3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66)(4,34)(5,65)(6,32)(7,63)(8,30)(9,61)(10,28)(11,59)(12,26)(13,57)(14,24)(15,55)(16,22)(17,53)(18,20)(19,51)(21,49)(23,47)(25,45)(27,43)(29,41)(31,39)(33,37)(36,66)(38,64)(40,62)(42,60)(44,58)(46,56)(48,54)(50,52) involution — undirectedA 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.