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