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