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