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