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