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