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