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)(11,22)(12,16)(13,21)(14,19)(15,30)(17,27)(18,23)(20,28)(24,33)(25,37)(26,35)(29,32)(31,38)(34,40)(36,39) involution — undirected(1,3,4,8)(2,5,6,7)(9,11,23,24,14,12,13,26)(10,16,18,35,19,22,21,33)(15,25,39,40,29,27,28,31)(17,36,38,32,37,20,34,30)(9,12,14,11)(10,17)(13,26,23,24)(15,31,29,40)(16,32)(18,34)(19,37)(20,33)(21,38)(22,30)(25,39,27,28)(35,36)(2,6)(5,7)(9,13,14,23)(10,18,19,21)(11,24,12,26)(15,28,29,39)(16,33,22,35)(17,34,37,38)(20,30,36,32)(25,40,27,31)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.