Not sure exactly what you want either, but on Notepad++, you can search and replace certain keys. For example...
Press Control + F (brings up the Find function).
Click on the Replace tab.
In "Find what": Input your color here. For example, "f0f0f0".
In "Replace with": Input your wanted color here. For example, "efefef".
Click Replace All on the right.
This will replace all instances of f0f0f0 with efefef.
My signature :)