What colour were you thinking of painting it ?
Any colour other than white lol, maybe to help it blend into its surroundings.
Colours other than white will probably absorb more solar radiation, potentially influencing the temperature sensor. For example, when the decks on my houseboat were white I could walk on them during the summer heat barefoot. I can't do that when they are mission brown as my feet burn - although a bit hotter than Hamilton, I guess.
Also be aware that you will need to confirm whether the paint you wish to use will adhere to the plastic, or whether you will need an undercoat. I was given a few of Campbell Scientific radiation shields that had discoloured and found a paint that has good adhesion directly to the plastic, but it was a white spray can designed to touch up air-conditioning vents, so I have no idea if it comes in different colours. Spray paint can be very wasteful due to over spray if you aren't careful.