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