How to capture the blues and greens of a landscape better?

Well, I was out hiking in yellowstone and attempted taking a few shots with my Nikon D5000 and its 55-105mm lens. It was cloudy, I had the ISO at Lo-1 (100), the White Balance at Cloudy, the exposure at +0, and the Aperture at f/16. I noticed that when I took a picture of the landscape, the greens and blues were far too faded and the entire scene was a bit reddish.

Even the landscape mode brought out the greens and blues better. What is it that I should modify in order to bring these colors out?

Added (1). You have helped greatly. I just have a question: How do I increase/decrease contrast?

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For cloudy days I like my ISO at the 200 range.

I try not to use the +/- settings on the ISO. 200-1600 is the best range. For landscape, ISO 200 is the choice.

The white balance is usually better to shoot with WB auto using RAW, correct in post. You can set the manual white balance far enough off that it can't be saved. If you use auto WB, then it is usually pretty close, so if it's off, it's not off by much. Shooting RAW lets you make more corrections to the photo.

The other one is to keep the aperture around F8.It's the center of the dial, that's where the shots are the best. F4 causes lens distortion, F16 or 22 causes distortion from the light being squeezed through the aperture.

The other suggestion is to use a polarizing filter, that will help give the colors more punch.

If the color is off, check your white balance, possibly trying out Auto first. If you could post some samples, that would be good.

Also, a polarizer could help with making the sky bluer and grass greener, but on cloudy days, this could differ.

You did everything right so far. Now in post, you will have to bump the contrast up to make up for the loss in contrast due to the cloudy day. The greens and blues will enhance with the contrast change. Use a light hand and don't over correct.

Remember the blues and greens actually were subdued in that lighting, so just a little contrast increase will bring them up to what you actually saw.

If you shot RAW + JPEG, you can process the RAW files and use the Auto mode in Lightroom if you like and see if that gives you what you want.

You may find that just leaving the image as it is with its subtle blue and green shades, it may start to grow on you.

You know to always save any changes to your original file as a different name, right? That way you can always come back at a later date and make other changes as the image grows on you