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