The minor pentatonic scale can be played in any key. Shown below is the open position fingering for the E minor pentatonic. Notice that this is the same as the A minor pentatonic from the 5th fret, moved down so that the nut replaces the first finger. This results in open string notes being used on all six strings.
Here are some riffs derived from the E minor pentatonic scale. Learn them from memory and then use the ideas to invent some of your own licks. Good players often improvise riffs when they are playing live, so the more practice you have at this, the better.