These are not "different Qurans." They are different linguistic accents and phonetic variations revealed by Allah to ease recitation for different Arab tribes (as mentioned in Sahih Hadith).
Digital archives like Internet Archive and platforms like Scribd host several prominent versions: mushaf qiraat sab 39-ah pdf
While this includes the "Ten" recitations, it is the most common comprehensive PDF for studying variant readings. Intro to the Sciences of the Quran: Sheikh Yasir Qadhi These are not "different Qurans