I have used Drontal oral suspension for puppies twice now  (correct amount for pups weight)  and both times my pup seems of colour the next day.
Is this normal after use of Drontal Liquid?

For this reason Im thinking I should change my wormer.

I use it and have never seen that reaction at all. I do know some wormers don't suit some dogs and for instance I won't use Panacur, whereas many others have no problems with it. So it may be best if you try a different one.

I agree with Goldmali, I've not had a problem with Drontal, heard of many problems with other wormers and would definitely steer clear of Panacur with my pups, depending if you've a 'herding' breed I'd also steer clear of ones with ivermectin in.

I have always used Drontal and never had a problem.

and I and many others use Panacur with no issues (always on a full stomach after a meal).  All wormers are strong chemicals so some mild reaction, a bit less hungry or a little looser than normal is to be expected.

Just doing my pups on their second day, just last dose tommorrow and finished until next time.