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