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