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