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