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