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