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