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