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