According to a chart I have, they read similar to a resistor.
On those Bumble Bee caps, the first two color bands are the value, the
3rd band is the number of zeros. The 4th band is the tolerance (%).
After a gap, there are supposed to be two more bands that tell the voltage. Yet, looking at a few of them that I have laying around, and pictures of the ones being sold on ebay, I have yet to find any of them that have TWO bands for the voltage.
For example, I have a picture of one right now that has ONE yellow band. That means "4", which I would consider to be 400v. Is this correct? Apparently this chart is defective, or else theye stopped using a dual band for the voltage at some time.....
Most of the time, I've just read the schematic and not bothered with the band colors, because nearly every cap I use as a replacement is rated at a higher voltage than the originals anyhow.