Well, it depends on what you mean by "can be found".
Maybe this FAQ will help you to understand:
How long do the images generated by PlantUML Server live for?
Links to png or svg generated by PlantUML Server are valid forever (that is as long as the server is up).
However, we do not store any diagrams on our servers.
This may sound contradictory. It is not: the whole diagram is compressed into the URL itself. When the server receives the URL, it decompresses the URL to retrieve the diagram text and generates the image. There is no need to store anything.
Does it help?