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