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