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