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