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