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