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