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