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