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