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