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