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