You cannot make a photograph "stands out (w/out being artificial)" if the picture itself is taken on a cloudy / dull day. I supposed you are familiar with PS; so the basic adjustments using levels &/or contrast for a start for the overall pic involved. It should, at least, bring out the full dynamic range of the said picture.
For more fine tuning, you have to dabble with curves.
You will have more leeway if your photograph was taken in the "RAW" format but nothing beats maximizing the situation at hand when taking the pic at the point of time (ie, setting the right in-camera settings - contrast, WB, etc).