You cannot calibrate a digital camera. You can, to a lesser degree, adjust how the camera sensor's output is converted into a color image; but I think "calibrate" might be too generous of a term for that.

What can, and should, be done to ensure accurate colors is to make sure you use a full spectrum light source to illuminate the paint chips... e.g. flash and not LED. And that the white balance of the image is adjusted for any color bias of the light source used (e.g. if halogen bulb was used instead of xenon flash).

Using a full spectrum light source ensures that the paint chips can reflect/absorb all wavelengths as they naturally would (i.e. in sunlight). The white balance adjustment can be done using a color checker target like the IT8; or using any known greyscale target (kodak grey card). Take a picture of the test target, and use the white balance adjustment/settings for all other images.

Calibration of digital images is mostly achieved by calibrating the output device; i.e. the monitor or printer that will create the viewable image. But since the image files are for archive purposes, you really will not have any control over that in the end; so that calibration step can be left for whoever is wanting to view the images in the future.

Also, get the exposure as accurate as possible at the time of recording because exposure shifts in post will also affect/change the color accuracy of raw files (because it changes the RGB luminance values that are demosaiced into the displayed colors).