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