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