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