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