Colouring one column of pandas dataframe

You can solve it in one line like this:

df.style.set_properties(**{'background-color': 'red'}, subset=['A'])

where subset is the list of column names on which you want to apply the desired properties.

The result is the same as shown by @jezrael You can check other properties and possibilities for styling in pandas' website

I think you need custom function which return DataFrame with color for first column:

np.random.seed(100)
df =  pd.DataFrame(np.random.randn(5, 3), columns=list('ABC'))

def highlight_col(x):
    r = 'background-color: red'
    df1 = pd.DataFrame('', index=x.index, columns=x.columns)
    df1.iloc[:, 0] = r
    return df1    
df.style.apply(highlight_col, axis=None)