Color Sensor/hi-tech and EV3
This is from page 87 of a document showing how to run NXT bricks using EV3-G software.



It uses the light sensor, not color sensor.  You'll want to set the mode of the color sensor.

Inside a loop that will stop following a line if the left button on the brick is pressed.

Basically, the steering value of the motors is taken from the light sensor reading.