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