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