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