> I sort of wonder is there a "true" way to represent color? Would an intensity over frequency curve do it?

There’s no single “true” way because color isn’t a fixed property of light itself, it’s the result of how a visual system interprets wavelengths.

Having said that, if you’re looking for an objective way that doesn’t depend on observer, you could use spectral power distribution.

That would be the mix of wavelengths present, plotted as intensity vs. wavelength.

That’s because a single wavelength (say 580nm) produces one specific color sensation, but many different combinations of wavelengths can produce that identical sensation (called metamers), so representing color by wavelength alone isn’t even uniquely “true” perceptually.

It’s actually even worse because, as countless color illusions demonstrate, our perception of color is a result of much more than just the spectral power distribution of the light.