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