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