"Why do you like to draw?"
Translation:¿Por qué te gusta dibujar?
Remember tu (without an accent mark) means Your.
The question in Spanish is, ¿Por qué te gusta dibujar? Why does to draw (drawing) please you? (Why do you like to draw)
You (te) are the recipient of the pleasure (gusta) which is brought about by the action of the verb (to draw-dibujar).
An example of using Tú would be, Tú dibujas muy bien. (You draw very well.)
https://studyspanish.com/grammar/lessons/gustar Gustar and encantar (and a few others but I don't know which ones) are different than most verbs. As explained in the site above, in Spanish, the sentence gets turned around a little bit and the person doing the liking becomes the indirect object, hence "te" instead of "tu," while the thing being liked is the subject of the sentence. It's a concept that definitely takes practice to get used to!
In short, your sentence is correct.
The subject in the sentence is actually to draw. A literal translation would be "why is drawing (to draw) pleasing to you?"
You is actually the object of the sentence. If you want to make the object plural you can use "os" (from the word vosotros- you plural informal) which is more commonly used in Spain. Or you can use "les" (ustedes - you plural formal) which is more common in latin american countries.
"Por qué os gusta dibujar" "Por qué les gusta dibujar"
Te gusta is the tú form. If you want to use the usted form, you need le gusta. Additionally, you need to use a before the usted if you're including it, so I think the full sentence would be: "¿por qué le gusta a usted dibujar?" or "¿a usted por qué le gusta dibujar?".
Regarding where exactly in the phrase you can insert the words a usted, I'm not totally sure... I just found a couple examples of similar phrases online and copied the word order. So if anyone else knows more about the word order, and knows if it's okay to add a usted at the very end, please expand on my answer :)
The pattern is:
[a ti] te gusta [...]
You could optionally add a ti in front of the te, but you don't use tú with te gusta.
The technical reason is because tú is a subject pronoun, which means you use it when "you"/tú are the one doing an action. But with gustar, the subject is actually the thing that pleases you, not the person who likes it: thing of it as "why does drawing please you?" instead of "why do you like drawing?". That's also why the conjugation here is gusta (the él/ella - "he"/"she"/"it" conjugation) and not gustas (the tú - "you" conjugation). This might help explain further: https://www.spanish411.net/Spanish-Using-Gustar.asp