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