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