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