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