Visually speaking, USB 3 ports are typically blue, so you can easily differentiate them. They also have 2 extra pins.
It is impossible to differntiate versions 1.0, 1.1, and 2.0 from each other visually. However, a computer would have to be pretty old to have version 1 or 1.1 ports. I believe anything on a Pentium 4 or later would be v2 and up.
See the following image to see the difference between version 3, and what is most likely 2.
Also, yellow ports typically designate powered ports, which can be always on to charge your devices.