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