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)(11,14)(12,16)(13,15)(17,21)(18,20)(19,22)(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)(1,3,7,4)(2,5,8,6)(9,11)(10,14)(12,18)(13,17)(15,21)(16,20)(19,23)(22,24)(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)(1,4,7,3)(2,5,8,6)(10,15)(11,17)(12,19)(20,24)(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)(1,5,7,6)(2,3,8,4)(9,12,13,19)(10,16,15,22)(11,18,17,23)(14,20,21,24)(26,34)(27,38)(28,41)(35,44)(39,45)(42,43)(46,50)(52,56)(1,6,7,5)(2,3,8,4)(11,17)(14,21)(18,23)(20,24)(26,34)(27,38)(33,48)(35,44)(37,53)(39,45)(40,49)(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.