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