How to have different colors in each Terminal window
I may not be understanding the question fully, since you change the color settings per-tab/window contrary to your question, but here is how to do what I think you want.


Go to Terminal menu > Preferences.
Click on the Settings tab.
Click on the gear icon at the bottom left and choose Duplicate Settings.
Enter a name for your settings.


Make any changes you want to font colors.
Repeat steps 3 through 6 until you have as many sets of colors as you want.
Close the Preferences window.
Open as many tabs as you want (3, it sounds like).
Right-click on the first and choose Inspect Tab.


Select your desired Settings pre-set from the list. (The ones you created will be down towards the bottom.)
Close the Inspector window.
Repeat steps 9 through 11 until you have customized each tab.


That should be it. If you want Terminal to always open like this, with these three tabs and their associated color settings:


Go to Window menu > Save Windows as Group.
Enter a name.
Click Save.
Go to Terminal menu > Preferences.
Click on the Startup tab.
Next to "On startup, open:" choose the radio button for "Window group:" and select the name of the group you created in step 2.