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