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