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