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