ggplot and color definition of different levels in figures

Welcome to the forum.
We need some idea of what you have tried and some sample data. See:

A handy way to supply some sample data is the dput() function. In the case of a large dataset something like dput(head(mydata, 100)) should supply the data we need. Just do dput(mydata) where mydata is your data. Copy the output and paste it here.