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