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