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