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