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