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