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