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