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