it's a blue circle if you use the default HUD colors.
things I've learned:
-its easier to find some of the artificial POI's (the kind with lights) on the dark side, or on icy planets
-land near the edge of the circle, jumping in your SRV and head towards the center of the circle (direction your ship is pointing) until you see signals on the wave scanner near the top, then focus on that direction.
-sometimes there is more than one object of interest in a single POI zone.
-on low gravity worlds, sometimes it helps to fly inverted and look "up" (which is now down) as it provides a better view of the ground.