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