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