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