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