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