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