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