MUTLI-COLORED LINE FOLLOWER ROBOT

hi guys!.

i just want to ask if it is possible to build a robot that can follow different colors in a single track. For example, the track is composed of 5 colors like, red,green,blue,yellow and orange. I haven't seen a line follower robot that follows different color in a single line. Also, i found out this $2 Color Detection Sensor - Tutorials - RobotShop Community and How to Build a Robot Tutorials - Society of Robots as basis to make my color sensor. But the problem is the response rate of LDR is slow and I have no idea what are other alternatives. Can somebody suggest me on what to do or is this possible to make?.. thanks in advance!.

what are other alternatives

Photo diodes/photo transistors.

Is there something wrong with your shift key?