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