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