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