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