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