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