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