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