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