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