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