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