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