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