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