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)(11,15)(12,16)(13,14)(17,18,20,22)(19,21,23,24)(26,30)(27,33)(28,36)(38,40)(2,4)(6,7)(10,14)(11,16)(19,23)(21,24) involution — undirected(1,3)(2,6)(4,7)(5,8)(9,11)(10,12)(13,16)(14,15)(17,18)(19,24)(20,22)(21,23)(25,26,29,30)(27,34,33,31)(28,32,36,37)(35,40,39,38)(1,3)(2,6)(4,7)(5,8)(9,12)(10,11)(13,15)(14,16)(17,19,20,23)(18,21,22,24)(25,27,29,33)(26,31,30,34)(28,35,36,39)(32,38,37,40)(1,4,5,2)(3,7,8,6)(9,10)(11,12)(13,14)(15,16)(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.