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