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