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