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