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