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