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