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