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