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