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