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