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