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