To my knowledge this is not supported directly. I've taken an approach, that while a bit complicated, yields great results:
1. I create an Excel workbook "template" that looks exactly how I want it to look (colors, multiple tabs, fonts, etc.)
2. Save this spreadsheet with the filetype of XML spreadsheet 2003 *.xml.
3. This is the hard part: reverse engineer the XML file using JSL. This requires knowledge of JSL and some understanding of XML.
JMP 12 will automatically save colored data table cells to the Excel spreadsheet.