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