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)(11,15)(12,16)(13,17)(14,18)(19,23)(20,22)(21,24)(25,26,28,30)(27,33,34,40)(29,37,36,32)(31,38,39,35)(2,5)(6,7)(9,11)(10,15)(12,20)(13,19)(14,21)(16,22)(17,23)(18,24)(26,30)(29,36)(33,40)(35,38) involution — undirected(10,16)(11,19)(12,13)(17,18)(20,21)(22,23)(25,27,28,34)(26,31,30,39)(29,38,36,35)(32,40,37,33)(1,3,4,8)(2,6,5,7)(9,12,14,13)(10,16,18,17)(11,20,21,19)(15,22,24,23)(26,30)(31,39)(32,37)(33,40)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.