Hello Oscar,
You can change the color of the Grid displayed on General Arrangement drawings, by modifying a default.
Go to the GRAITEC Advance Manager > Settings > Defaults > Drawing - Presentation > Colours, and modify the colour for "Colour of grid lines on drawings" => the next time you will create a view showing the grid, this grid will get this colour automatically.
Remark: this default affects all the grid (axis, texts and balloons)
Regards
Philippe