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