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