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