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