Well, unfortunately they didn't make glass in lots of colours in the middle ages.
Very little in The Visitation remains from the 14th century. The head of Elizabeth is medieval and some of the top yellow accents in her pane and in Mary's are just about it.
The Annunciation contains a lot more original glass, which is why it is loaned out to medieval exhibitions.
The red shaded area in the image below corresponds directly to the right hand pane, and indicates the original 14th century glass.
You will see that most of Mary is in clear and yellow glass that has been painted on to give texture. That is then fired to set it. The yellow glass is made using silver stain, which is mixed with the sand etc when the make the glass. This was about as much colour as they could create back then. Gabriel's wing has a lot of black paint added to create texture.
The windows were heavily restored in the Victorian era, which means that the bright reds and blues were added in the 19th century.
I've put the two images below so you can match it directly for yourselves.