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