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)(11,21)(12,16)(13,20)(14,19)(15,18)(17,23)(22,24)(25,26)(27,30)(28,31)(29,32)(33,37)(34,36)(35,38)(39,40) involution — undirected(2,5)(6,8)(9,11,14,12)(10,16,19,21)(13,23,15,22)(17,20,24,18)(25,27,29,34)(26,30,32,36)(28,33,35,39)(31,37,38,40)(1,3,4,7)(2,6,5,8)(9,12,14,11)(10,17,19,24)(13,23,15,22)(16,20,21,18)(28,35)(30,36)(31,38)(33,39)(2,5)(6,8)(9,13,14,15)(10,18,19,20)(11,22,12,23)(16,24,21,17)(25,28,29,35)(26,31,32,38)(27,33,34,39)(30,37,36,40)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.