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