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