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