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