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)(11,15)(12,19)(13,14)(16,20)(17,21)(18,24)(22,23)(25,26)(27,37)(28,31)(29,34)(30,35)(32,36)(33,39)(38,40) involution — undirected(1,2,4,6)(3,5,8,7)(11,17)(15,21)(18,23)(22,24)(25,27,32,39)(26,33,36,37)(28,38,29,30)(31,35,34,40)(1,2)(3,5)(4,6)(7,8)(10,14)(15,21)(16,19)(22,24)(25,28,32,29)(26,31,36,34)(27,38,39,30)(33,35,37,40)(1,3,4,8)(2,5,6,7)(9,10)(11,15)(12,16)(13,14)(17,21)(18,22)(19,20)(23,24)(25,29,32,28)(26,34,36,31)(27,30,39,38)(33,40,37,35)(9,11,13,17)(10,15,14,21)(12,18,20,23)(16,22,19,24)(25,30)(26,35)(27,28)(29,39)(31,37)(32,38)(33,34)(36,40)(9,12,13,20)(10,16,14,19)(11,18,17,23)(15,22,21,24)(25,31,32,34)(26,28,36,29)(27,35,39,40)(30,33,38,37)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.