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