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