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