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