That was a limitation of the monitor you were using, not the computer. All models of Apple II to include the Plus, e and c had color graphics. But it was common practice to pair them with monochrome monitors, first because they're cheaper than color monitors, but also...the way the Apple II achieved a 16 color palette was through NTSC artifacting. It only ever tried to send something like six colors over the cable, but when you put two dissimilar colors next to each other, they get smeared together somewhere in the analog domain and they come out some other color. It allowed them to achieve 16 colors, but it had a drawback: Text that was supposed to appear black and white would have green and purple fringes, which made it blurry and hard to read. So if you were using the machine for business or something you might choose a monochrome monitor to get sharper, easier to read text. Apple's first party monochrome monitors were indeed green.