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