One vertex per element, one color per generator, with an edge from x to x·s.
(5,6,13,38,29,53,31,14,11,19,9,30,36,50,39,43,12,17,33,64,28,49,26,42,35,51,8,16,10,18,41,54)(7,20,56,46,34,65,27,15,24,59,22,52,62,48,63,47,25,44,61,67,60,68,32,45,37,66,21,57,23,58,40,55)(1,2)(3,4)(6,14,17,42)(8,26)(9,31)(10,29)(11,35)(13,39)(15,44,45,20)(16,18,30,50)(19,54,51,43)(21,32)(22,27)(23,34)(24,37)(28,36)(33,41)(38,49,64,53)(40,61)(46,68,67,65)(47,59,55,66)(48,57,58,52)(56,63)(60,62)(2,4)(5,7,12,25)(6,15,17,45)(8,27,9,32)(10,34,36,60)(11,37,35,24)(13,40,33,63)(14,20,42,44)(16,48,30,58)(18,52,50,57)(19,55,51,47)(21,26,22,31)(23,28,62,29)(38,65,64,68)(39,61,41,56)(43,66,54,59)(46,49,67,53)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.