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