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