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