I see this going one of two ways:

1. The signal strength decides what colour the lamp glows, so 0 for black, and then follow the colours as in how they're sorted in the bedrock inventory (black, grey, light grey, white, brown, red...). It could be crafted using 4 glow ink sacs and 1 regular lamp.

2. 16 individual bulbs with the colours, crafted with 4 of a coloured dye and 1 lamp.

Also, I understand that this probably won't add coloured light to the game (if it even gets added), but the Froglight is nice in a lot of builds and it's coloured. I can also see the first one being used in some sort of hexadecimal calculator with a key. 1.21 is already going to add a binary and decimal counter, so why not throw in hexadecimal?