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