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