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