Not a very big guild. Very small actually. Only about eight people. The thing is, there isn't much paint in the entire city. So if paint is acquired, the guild spends a lot of time lobbying about who'll get his or her house painted.
Many of the esteemed folk in the upper town desire a coloured house, since it has become a symbol of luxury and power.
So, despite being very small, the guild has a lot of sway in the city.