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