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