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