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