I would like to see the constellation diagram after equalization as shown in the website Correct constellation for QAM. But I am getting a different plot. Can somebody please tell me where I am going wrong?
You are getting the correct constellation. You need to remember that you added noise to your symbols in the channel, So, you won't get a perfect constellation as you have in the first figure. Try increasing SNR (EbNo) and you will see better the constellation.
This is what I got: