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