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