First of all, I think its obvious what Naruto's favourite colour is. From Genin to Kage, he maintains his signature orange colour.
The poppy orange colour was not only focused to make Naruto's appearance pop to the readers/viewers. There were several other factors:
The fact that Naruto's signature colour is a result of the mixture of the signature colours of his parents, is a significant reason for its implementation.
- Naruto's childhood was a very rocky one. The villagers used to isolate him and ignore him. Due to which, Naruto would put up acts so he would be noticed or appreciates or be cared for. The poppy orange plays a crucial role here. Combining the two logic, i.e., orange pops out and Naruto wanted to be noticed, his dress code makes sense.
Some other factor(s):
Due to the Kyuubi being orange in colour. Kishimoto purposefully made Naruto and Kurama's colour scheme similar so they would look more related. This is something that I read a while back. It makes sense, but it's just an unsourced info.
Here's another factor I found while going through the post, Why does Kakashi Hatake always wear a mask? (credit to @InfantPro'Aravind'):
@user1526, adding to starPilot's, color orange signifies ENERGY, a will to be sportive and always ready .. that's the character of Naruto .. – InfantPro'Aravind' Mar 17 '13 at 13:23
As for in-universe talks about his dressing, I couldn't find any reasoning or questioning references.