Cologne is a bottom team that has not improved in performance so of course Leipzig will be the favorite to win the match.
The great motivation for Leipzig to finish in the top 4 makes me have no doubts about betting on the same thing as you, namely on Leipzig winning, I think they will win this match easily.
You are right that Cologne is on of the Teams that are at the bottom on table , but they played last weekend a 3:3 draw against Gladbach.
So there is a chance that they have took some energy out of that last game and bring that on the field today.
But i guess it will be not enough against Leipzig as they are for sure want to win , fingers crossed our bet will come true.