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