The short answer is that you can’t unless you keep the piece in a dark closet or a shoe box. The fact is that there is no finish that will eliminate the effects of UV light which affects all woods. You can use a marine varnish with UV inhibitors. That will delay the color change slightly, but it can’t be eliminated.
The best approach is to accept that the wood color will change and create a design that will look good today and in 10 years. For example, don’t put similar color woods together because they will likely look the same sometime down the road.
