Changing screen colours can be easily done using the .NET [Console] object with commands similar to below:
[Console]::ForegroundColor = "yellow"
[Console]::BackgroundColor = "red"
After changing the background a Clear-Host command should be issued.
To put the colours back to the default issue the following command:
[Console]::ResetColor()
Again, if you have previously changed the background colour and are reverting it you will need to run Clear-Host