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