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