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