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