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