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