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