Is it correct to say that Islam is an Evolution of Nestorian Christianity? I often see infrographics that make a connection between them.

No. It's a gross oversimplification that unknowingly or not engages in stereotypes and depictions of Muslims and Islam in general going back centuries.

So, there actually is a medieval life of Muhammad that does explicitly connect the origin of Islam to a conspiracy between Nestorius, condemned as a heretic, and Muhammad himself. In this text Muhammad and Nestorius conspire to fool the Arab people into believing their new way of life and the conspiracy involves tying parchment to a bull's horns and depriving it of water for three days. Muhammad later murders Nestorius in order to not share his fame.

With these words, this agreement everyone returned to his own affairs; only Muhammad remained alone with Nestorius, and he was not at a loss. he had indeed for this purpose a teacher who would not desert himt o show him by what trick he should achieve his plan. He said "O father Nestorius, I have a plan for our undertaking, quite, as it seems to me, useful, necessary, and plausible, that I offer for your choice. Let the task and responsibility be yours-nay rather if you command, let them also be mine along with you, more quickly than you will be able to [alone], to set doen specifically and clearly according to a careful scheme on parchment what to do, what to avoid, indeed all aspects of how to live, what to believe, and how to worship. You will tie this document to the horns of a heifer that shall be shut up two days without drinking, and on the third day it shall be sent forth. Then you will see what follows.

Translation by Julian Yolles and Jessica Weiss, Medieval Latin Lives of Muhammad, Harvard University Library, 2018.

It should almost go without saying that medieval Latins were not particularly interested in an accurate and objective process for determining where Islam originated from. Indeed there are all sorts of issues attempting to draw a firm line from Nestorius, former patriarch of Constantinople, condemned as a heretic for his beliefs on the dual nature of Christ, and Muhammad who lived about a century and half later, in Arabia. Nestorius's beliefs were not stamped out because of this one council, and churches that supported his ideas remained in existence throughout the middle east.

As for explicit connections between the beliefs of Nestorius and Muhammad, well Nestorius was still a Christian, even if he was condemned as a heretic for his teachings on the dual nature of Christ, Muhammad was not. Efforts to explain Islam as an offshoot or evolution of a heretical variant (according to the Catholic and Orthodox Churches even if they weren't there yet in the 5th century) of Christianity tells us far more about the source of the claim than it does about the truth of the origins of Islam.

Now unfortunately I do not know a great deal of the origin of Islam in and of itself, but I do hope that this gives you a bit of context on where the connections between Nestorius and Islam come from.