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