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