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