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