from IPython.display import display, HTML
import pandas as pd

dic = {
    '国旗': ['日本', 'アメリカ'],
    '色': [
          '白、_RED_START_紅_END_',
          '白、_BLUE_START_青_END_、_RED_START_赤_END_'
        ]
}
df = pd.DataFrame(dic)
df

html = df.to_html()
print(html)
display(HTML(html))

html = html.replace('_RED_START_', '<font color="red">').replace('_BLUE_START_', '<font color="blue">').replace('_END_', '</font>')
print(html)
display(HTML(html))