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