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