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