You are not going to get new growth for a while. It is just adjusting to being moved. Since it has been planted recently the blooms will probably fade and die much faster than they will next year. I think I would just do nothing right now and wait and see what it does next year. It is a shrub that will take a while to root and start growing, it just needs some time. Also for most hydrangea that bloom color can change quite a bit as it goes from first blooming to fading away. Mine started white, then turned pink, next a dark burgundy and finally dried and was a tan/brown just before winter.
