All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
In principle, this water or any other water that touches you is pure, and you do not rule that it is impure unless you are certain that it has been changed by an impurity.
If it is possible that its color has changed because of other pure things that were mixed with it or because of an impurity, then in principle it is pure.
Therefore, it is permissible for you to pray while stained with this water. If you are absolutely certain that this water has changed because of an impurity, then in that case, you must wash the spots on your body or clothes that are stained with this water when you want to pray.
Allah knows best.