Watch the Diagonal Lines online guitar lesson by Jon Finn from 30 Melodic Modal Rock Licks You MUST Know
This lick is centered around D Phrygian. There's a couple of places I've incorporated an Eb major 7 arpeggio, which looks just like a diagonal line across the fretboard.
The main feature in this lick is where it starts. It begins on a pickup on the "and" of beat 3. It's a series of arpeggios with nice wide intervals. Check the notation and tablature to get the finer details. Practice with the backing track, then invent your own version of this lick!