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