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