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