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