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