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