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