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