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