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