Powershell ISE with Powershell Version 4.0+ Includes some good coloring features for interactive scripting.

Powershell v2 ships with Windows 7, v4 can be downloaded and ISE is on the machine already. Current powershell version is v5, but beware-- some software like Server 2008 R2 running Exchange 2010 is built on v2, and a lot of the cmdlets won't work for v3-v5 without PS-Sessions.
In case you were curious about coloring output to the host, you can just do
Write-Host "my string" -fore 'color' -back 'color'
If you want a fully-fledged powershell IDE, you can purchase SAPIEN Powershell Studio which also wraps scripts in Windows Forms, can build MSI packages and similar things. If you're a hard core powershell kind of guy, it may be worth your time if making GUI powershell applications.
PSReadLine.