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