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