One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,6)(5,8)(9,10)(11,16)(12,14)(13,17)(15,18)(19,22)(20,24)(21,23)(25,26)(27,33)(28,30)(29,37)(31,35)(32,36)(34,39)(38,40) involution — undirected(1,3,4,8)(2,5,6,7)(9,11,15,22)(10,16,18,19)(12,23,17,24)(13,20,14,21)(26,30)(27,34)(29,36)(31,38)(9,12,13,18,15,17,14,10)(11,19,20,24,22,16,21,23)(25,27,29,35,28,34,36,40)(26,31,32,33,30,38,37,39)(2,6)(5,7)(9,13,15,14)(10,17,18,12)(11,20,22,21)(16,24,19,23)(26,30)(31,38)(32,37)(33,39)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.