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