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