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