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