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)(27,31,36,42)(28,32,39,45)(29,33,40,46)(35,41,47,51)(37,43,49,53)(38,44,50,54)(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)(28,38)(29,40)(31,41)(32,44)(33,46)(36,47)(37,49)(39,50)(42,51)(43,53)(45,54)(2,6)(5,8)(25,27,29,35,30,36,40,47)(26,31,33,41,34,42,46,51)(28,37,38,48,39,49,50,55)(32,43,44,52,45,53,54,56)(9,12,14,13)(10,16,17,21)(11,19,20,22)(15,23,18,24)(27,36)(31,42)(35,47)(37,49)(41,51)(43,53)(48,55)(52,56)(9,13,14,12)(10,16,17,21)(11,19,20,22)(15,24,18,23)(25,28,29,38,30,39,40,50)(26,32,33,44,34,45,46,54)(27,37,35,48,36,49,47,55)(31,43,41,52,42,53,51,56)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.