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