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