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