From my understanding itis on there list as adding a filter to the colonies list.

That's one of my pain points as well.  There is no good way to filter the main map, or get a list of "these are the planets that you know about, but are not yet colonized".  So instead, I have to zoom out on the map and get eye strain from trying to find the white circle within circle that doesn't have a dot at the top and which doesn't look like a white dwarf star.

We either need a list - or better, the ability to filter the main map to show/hide features.

I agree - and the list should let you filter by various criteria like size or valuable resources so you could prioritise. And even so you could auto-build a colonizer at your nearest shipyard which would send it to the uncolonised planet of your choice.