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