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