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