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