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