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