To get to Banuta you must be on Mission 9 of The Ape City Quest. You must make your way into the first floors of Banuta and use the teleport. You can find it here or using the image below.
Once you enter this teleport you will be taken to the next floor with the 4 Canopic Jar to be broke. You can use the image below taken from TibiaWiki to see the location. I would recommend going clockwise and breaking each jar then going into the next teleport. You may also want to use a Dwarven Ring while running around as there are some creatures that can make you drunk. The Canopic Jars have to be broken within a certain time limit to active the next teleporter.
The blue circle is where you first land when you enter this floor. The green circles are the Canopic Jars to break. Lastly, the Yellow circle is the teleport that will take you to the next floor.
If you have broken the 4 Canopic Jars within the time limit and enter the teleporter found in the yellow circle you will be in deeper Banuta. If you wish to come back here using this route you must break the jars each time.
If you want to gain access to the shortcut you must bring an Egg of the Many with you. When you reach deeper Banuta you can find a snake head directly east of the teleporter that you use the Egg of the Many on. It can be found here:
Once doing this you have permanent access to come or go using this shortcut. To find the shortcut from the surface you must enter a hole and teleport here:
Following the tunnels through this shortcut will take you to the teleport found by the Snake Statue where you originally used the Egg of the Many. The only thing you will really have to watch for when using this shortcut is 2 Giant Spiders.