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