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