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