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