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