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