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