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