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