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