I decided to make a map in Paint. It does not look good, but it is also inaccurate.
I'll probably make better maps in the future, but until then you'll have to settle for these two artworks.
The story has been taken without consent; if you see it on Amazon, report the incident.
This map has one little spoiler, but I don't think it will make much of a difference as you will know it in one or two chapters anyway.
Spoiler: Basic layout of the entire dungeon.
The brown dots symbolize the future floors. I was too lazy to draw them all.