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