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