You can Create a master Sheet, Format it the way you need. Go To FORMAT>Copy Formatting>Paste Formatting
Tableau does support workbook-level formatting for fonts, so that's one option.
Colora are a little trickier. If you're using Tableau Server data sources, AND you have default colors for dimensions (West is green, East is yellow, etc), then changing them in the server data source will also change them in workbooks that use that data source.