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