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