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