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