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)(11,18)(12,16)(13,22)(14,17)(15,21)(19,24)(20,23)(25,26,29,31)(27,35,36,49)(28,39,40,33)(30,43,42,34)(32,45,44,38)(37,51,50,48)(41,47,55,54)(46,52,53,56)(1,3)(2,5)(4,7)(6,8)(9,11)(10,15)(12,19)(13,20)(14,21)(16,23)(17,18)(22,24)(26,31)(27,36)(33,39)(34,43)(37,50)(38,45)(47,54)(52,56) involution — undirected(3,7)(5,8)(9,12,14,13)(10,16,17,22)(11,19,21,20)(15,23,18,24)(25,27,30,38,29,36,42,45)(26,32,34,35,31,44,43,49)(28,37,41,52,40,50,55,56)(33,46,47,48,39,53,54,51)(2,6)(3,7)(9,12,14,13)(10,16,17,22)(11,20,21,19)(15,24,18,23)(25,28)(26,33)(27,37)(29,40)(30,41)(31,39)(32,46)(34,47)(35,48)(36,50)(38,52)(42,55)(43,54)(44,53)(45,56)(49,51)(3,7)(5,8)(9,13,14,12)(10,16,17,22)(11,20,21,19)(15,23,18,24)(26,31)(28,40)(32,44)(34,43)(35,49)(37,50)(41,55)(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.