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