The first thing you should do is color everything in this area first, and then go to the Blue Challenge area.  This First Challenge is to simply follow some flares.  While you are over at the end of the street, go ahead and paint that, including the trees.  Go ahead and paint 4 trees here.   

You will find that mid way on the street are some steps that will lead to the train above.  You will need to beat this in the Second Challenge.  From here, you will paint the First Billboard, the Second Billboard, and the Third Billboard. 

Sadly, it won’t let you ride the train and get the First Style which you can jump to at the end.  Go ahead and paint all you can down here, and then you will be told how to take out the Inkies with guns.  While you are here, you can do a jump that will cause you to roll toward the Fourth Billboard that is high over the highway. 

There is a challenge there, so go for it.  After defeating the Third Challenge, you should up and paint the rest of the block while you are at it.  You will release the First Raydian Batch.  By the way, there are other Raydians around here, which gives a total of 11. 

In this area is also the Second Style.  You will also find the Fifth Billboard. 

The Fourth Challenge arrow is here.  This involves tripping a lever to turn off a hot plate.  While you are at it, paint all the white buildings here.  Color the Sixth Billboard on the way there. 

Take on the Fifth Challenge.  You will paint the Seventh Billboard and Eighth Billboard on the way.

Completing the last challenge will open up the Sixth Challenge, which is to take out the Inkies here.  By the way, you should take out all the Inkies here. 

If you paint the whole area, you will free the Graydians.  There some other Raydians mixed down there, but if you paint this whole thing, you should have the Second Raydian Batch for a total of 22. 

Before you go through the gate, paint up that one building there.  You should notice that on the pipes is the Third Style, so make certain that you get it.  You will find the Third Raydian Batch for a total of 30. 

Nothing to do now but go ahead and open the gate.