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