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