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