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