Matrix showing all names per rating and performance

[dkjacchr]

Hi Experts

I am quite new to Power BI and need to create a matrix that will show all names of sales persons and their placement within a rating and performance matrix.

The outcome should be something similar to this: 

I can manage to show the count of sales persons in each segment as well as the first or last sales person's name. From from what I understand I need to create a measure where I can add a line break making it act like showing a row per sales person in a given segment. But how is this achieved?

Finally is it possible to color each "cell" of the matrix indiviually?