In April 1745 all militia grenadier companies were ordered to be detached from their parent battalions and grouped into 11 regiments of Grenadiers Royaux. Each regiment consisted of a single battalion. In January 1746 a decree stipulated that there would be a new company of grenadiers in each militia battalion, called Grenadiers Postiches. At the beginning of the Seven Years War the Grenadiers Postiches were detached from their parent militia battalions and incorporated into the 11 existing Grenadiers Royaux regiments, increasing them from 1 to 2 battalions each.
Grenadiers Royaux regiments wore the same uniform, distinguished only by different coloured collars and epaulettes on the right shoulder. All wore the tricorne laced silver.
Information summarised from Kronoskaf and the histories of the different regiments can be found at Kronoskaf here: http://www.kronoskaf.com/syw/index.php?title=French_Army#Militias
Each regiment carried only ordonnance flags as shown below:
And this plate shows the uniform and flags in 1757: