@Suiseiseki @SuperDicq @koakuma

Don't forget --suppress-common (can be shortened to --suppress-c). Also, --side-by-side has a shorthand version: -y

In summary:

diff -y --suppress-c --color file1 file2

However, some brief testing seems to indicate that --color makes no difference in the side-by-side mode of operation. It doesn't seem to use color. Unfortunate.