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