Apart from the "coloring" part, I would definitely suggest you go for CSV files (perfectly supported by ALL spreadsheet programs) :
A comma-separated values (CSV) file stores tabular data (numbers and
text) in plain-text form. Plain text means that the file is a sequence
of characters, with no data that has to be interpreted instead, as
binary numbers. A CSV file consists of any number of records,
separated by line breaks of some kind; each record consists of fields,
separated by some other character or string, most commonly a literal
TAB or comma. Usually, all records have an identical sequence of
fields.
Example :
Year,Make,Model,Length
1997,Ford,E350,2.34
2000,Mercury,Cougar,2.38