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