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