As I understand it, this regiment was originally part of James II's army in exile and was formed in September 1691 as the Roi d'Angleterre. It was led by Domenick Sheldon. In 1698 it was merged with the Queens regiment and became the regiment of Sheldon as part of the French army.
In 1706 it became the regiment Nugent under the Comte de Nugent.
It seems that the blue cuffs and red coat was the uniform from 1735 and prior to that the coat was red with red cuffs, although several uniform books for the WSS show blue cuffs. The reference to the red cuffs is from 1730 so before that is not known for sure.
The flag was red with a golden sun on one side and an eagle on the other with the the motto "torn off". This may have referred to the loss of James's crown. This would have been the flag from when the regiment joined the French army. Maybe the eagle and motto could have pre dated that but the golden sun is the symbol of Louis XIV. Maverick models do a nice version of the flag. I think the GMB one is from the SYW.
Now the trumpeter livery, unfortunately there is no reference to that at all
so it's up to you. It would usually be the livery of the colonel in a non royal or provincial regiment.