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