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