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