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