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