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