In English, when people don't understand what you are saying, they might say "it's Greek to me". We can represent this relationship with a direct edge from an English node to a Greek node. This Wikipedia page collects similar idioms in various languages. We can construct a graph from this!
I was excited about this brilliant idea until I googled 'greek to me graph'. Of course, people have already done it. This post (2015) shows how to use python to parse the Wikipedia page and generate the graph, highly recommended.
Mark Liberman (he has his own Wikipedia page), a linguistics professor at the University of Pennsylvania, posted on this topic in 2009 (funny side note: the id of this post is 1024). His graph is shown below.
In 2017, this post was submitted to Reddit but only received 63 upvotes.
In 2021, this post was submitted to Reddit and received 17.9k upvotes. I guess the national flags and choosing the right subreddit helped.
In the end, I didn't make my graph - no need to reinvent the wheel. But it's interesting to see that my mother tongue - Chinese - is perceived as a very difficult language by a lot of people, which I totally agree with! It is not easy, but at the same time, it's so beautiful.