//Instantiate a new Workbook
Workbook workbook = new Workbook(dataPath + "workbook.xls");

//Get the first worksheet in the book
Worksheet worksheet = workbook.getWorksheets().get(0);

//Set the tab color
worksheet.setTabColor(Color.getRed());

//Save the Excel file
workbook.save(dataPath + "AsposeColoredTab_Out.xls");