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