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