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