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