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