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