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