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