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