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