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