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