For the advanced (gripflight required) route 'the moon points the way'. Follow the standard route until you see god rays from between two buildings. That's your exit. You'll converge with the intermediate route. When you see the wrecked junction against the moon, that's a hint that this section is another crossroads. There's a poster in the background that drops another hint - 'intellect climbs'. Look to the left of that poster.

For anyone checking for hints;
For the easier (but slow) route, just follow the track.

for the intermediate route, turn left at the first crossroads, on the opening straight. An overhead sign indicates the left turn is available just before you reach it. It will converge with the easy route after the tunnel. At the two pods with the light grid between them, there's a shortcut if you hop off the track - the road there is orange so should stand out against the background.
Finally, at the waste processing plant fall short on the jump. There's a second exit underneath the fan in the room with the purple light.