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