Legend in MS Project footer

[Antares]

Hi,

I have many tasks in my schedule and for easy eye identification some certain type of tasks (for example that have same resource), actually bars of those tasks I colored in some color, another type of tasks in different color...

So could you pls advise me how do I make a legend saying that for example green bars are those activities that use resource A, red bars use resource B and etc...

Thanks much