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