Hi Degen,

During the period of history in which people have been making measurements of the Sun's spectrum, I don't think that the overall color has changed dramatically. There are variations over the solar cycle in emissions from the Sun at certain wavelengths, like X-rays. You can look here for more information about the Sun in X-rays.

However, as the Sun evolves, it will change over time - and that includes its color. Right now our Sun is sort of yellowish in color, but as our Sun ages, it will eventually become a red giant star. Scientists use a fancy diagram called the Hertzsprung-Russell Diagram to help them understand how the color (spectral class), temperature, and mass of stars like our Sun will change over millions of years. It can help us understand what the Sun might have been like in the distant past, and what it might be like in the distant future.

Kris