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