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