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