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