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