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