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