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