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