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