The best way to stay warm after a shower is to use warm towels to dry off and wrap around you.
I have a towel warmer that I bought off ebay for $40.00 and it warms the towels up to keep me warm when I dry off after a shower.
When I take a shower in the winter I turn up the heater so that the bathroom and the rest of the house gets warmer than usual.
That helps to keep from getting my body cold after a shower too.
In the summertime I temporarily turn down the central air conditioner and allow the house to warm back up some.
That also prevents me from getting too cold after the shower.
Also if your bathroom has a window try letting in some sunlight.
My bathroom has a window that directs towards the shower which helps when the sun is shining because the sun shining helps to heat my body up through radiation of the suns rays.
You can also use a hair dryer to dry your body off faster than a towel.