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