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