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)(11,19)(12,21)(13,17)(14,16)(15,18)(20,23)(22,24)(25,26,30,35)(27,36,41,48)(28,42,46,51)(29,33,37,34)(31,40,49,39)(32,44,52,45)(38,50,43,47)(53,54,56,55)(2,5)(6,8)(9,11,15,14)(10,16,18,19)(12,22,13,20)(17,24,21,23)(25,27,37,40,30,41,29,39)(26,31,33,48,35,49,34,36)(28,43,44,55,46,38,45,54)(32,50,51,53,52,47,42,56)(1,3,4,7)(2,6,5,8)(9,12,15,13)(10,17,18,21)(11,20,14,22)(16,23,19,24)(25,28,29,45,30,46,37,44)(26,32,34,42,35,52,33,51)(27,38,39,55,41,43,40,54)(31,47,36,53,49,50,48,56)(9,13,15,12)(10,17,18,21)(11,20,14,22)(16,24,19,23)(25,29,30,37)(26,33,35,34)(27,39,41,40)(28,44,46,45)(31,48,49,36)(32,42,52,51)(38,54,43,55)(47,53,50,56)(9,14,15,11)(10,16,18,19)(12,22,13,20)(17,23,21,24)(25,29,30,37)(26,33,35,34)(27,40,41,39)(28,45,46,44)(31,36,49,48)(32,51,52,42)(38,54,43,55)(47,53,50,56)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.