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