Today's guitar lick comes straight out of Box 1 of the pentatonic minor scale. Elsewhere, I've often called this the root 6 pentatonic minor scale, because the root note for the pattern is on the 6th string.
Here's the tab:
The secret to this riff is mastering the repetitive picking motion. Down, pull off, up. Repeat. I find that this is the most efficient way of picking this sort of sequence, because your pick stays "inside" the two strings you're working with, thus limiting the distance it has to travel. If you picked in any other arrangement, your pick would have to travel further, which slows you down, even if only a little.
Feel free to "break" this riff and modify it to your heart's content. One obvious way of doing that is to change the number of times you repeat those three notes at the beginning of the riff. Perhaps try a whole bar of those, before getting into the rest of the riff?
Or, recognize that you're working with a pattern of notes, and simply pick three different notes to work with, applying the same picking pattern. Or, work your way through a scale pattern using this approach. Or, end it differently than I wrote it here.
The options really are limitless, and although I know that on one hand it doesn't help to say that without giving specifics, on the other hand, sometimes people need permission to break the rules and start colouring outside the lines.