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