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