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