"It depends"...
Colours generally take time to come through - from hatching up to 6-12 months or so the colours will probably get more and more vibrant and defined with each shed.
Beyond that, a lot depends on the line that he comes out of; some lines tend to start to lose their pattern, so the colour becomes more diffuse (but at the sametime more widespread). If the beardie is a couple of different colours you may notice them blending a bit, as the beardie changes to a more uniform colour all over. Others keep their pattern quite nicely, and start to "fill in" around the coloured pattern with more colour.
The environment plays a part as well - a balanced diet with a variety of veg will help with pigment production which can help them develop and hold their colour a bit better. A nice, intense UV source (or good natural sunlight) also seem to help, although I don't know how much of that is long term and how much is the beardie equivalent of "looking healthier" after a suntan.