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