I would put the pink button near (but not at) the top right corner, at the second row, four from the left, where it would make a dynamic assymetry, taking the eye forward and up in optimism.
I wouldn't like it at the equivalent points near each of the other three corners. Putting it at a point near (but not at) the lower right corner would still go forward, but dropping down.
Near (but not at) the left side, at row two, it would take the eye back and out of the picture, stopping the forward flow, and at row four near the left, the eye would go down as well as back, off the bottom of the page as well as off the side. .
This all relates to the eye movements trained into us as we learnt to read. We read from left to right. Also we raise our gaze when optimistic and drop it when sad. Many famous paintings can be "read" from left to right, and many "inspirational" scenes have lines which take the eyes up and to the right. (and hymns and psalms - "I to the hills will lift mine eyes" )