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