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