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