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