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