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