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