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