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