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