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