پسندیدہ رنگ یا پینٹ
According to your sentence this seems suitable.

I agree with the point made in discussion by Piyush Ojha that the website wants to clearly indicate that these colors are for general crafts and hobbies. In the US, something like "craft colors" would convey the meaning. "Craft" clearly implies something made by hand as a hobby. The closest relevant translation I can think of relates to 'handicrafts'...adding مشاغل to it to indicates casual hobbies and not skilled/professional handicrafts, because products for professional handicrafts probably come in larger quantities and have different safety ratings than those allowed for general public.

There is a brand called "Hobby Colors" but I don't think that is what this website implies. I would make a note when sending back the translation that they should inform if they mean the brand or just colors for craft activities.

Hobby colours may also be used for drawing and painting activities, besides handy crafts. So, using an Urdu with wider scope may work better. Following are more versions of the translation:

مشاغل/فراغت کی سرگرمیوں کے رنگ
مشاغل/فراغت کی سرگرمیوں میں استعمال ہونے والے رنگ

It is also a good idea to insert the transliteration in brackets after the translation to avoid any confusions.

Most of the times Hobby is spoken as شوق in Urdu.
For example: Collecting coins is his hobby. اسے سکے جمع کرنے کا شوق ہے۔