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)(12,16)(13,25)(14,18)(17,24)(19,29)(20,30)(21,38)(22,32)(23,33)(26,40)(27,34)(28,36)(31,39)(35,37) involution — undirected(1,3,4,8)(2,5,6,7)(9,11,19,22,12,23,14,28)(10,15,29,32,16,33,18,36)(13,26,37,39,24,20,27,21)(17,30,34,38,25,40,35,31)(10,16)(11,20,23,26)(13,27)(14,19)(15,30,33,40)(17,34)(21,22,39,28)(24,37)(25,35)(31,36,38,32)(2,6)(5,7) 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.