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