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