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