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