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