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