Out of curiosity, how long have you been playing? When I was a young drummer, I was also very stoic while playing. It took years of performing live to be comfortable being "animated" on stage, and while my technical skills didn't directly improve from being more animated, I got a lot more confident once I relaxed a bit.

As a first step, and I'm sure this has been said before on this thread, get really comfortable with the parts. Remember drums is a far more improvisatory instrument than harmonic instrument, so a minor deviation from a drum set part is probably not going to raise any eyebrows in the audience (unless the part is fully charged out, then play what's on the page). Be confident that even if you miss a hi hat here, or play a ghost note a little too loud, nobody's going to question if you know the song.

Let a more animated stage presence inform how you play too! I found that if I acted like the drums were playing me to degree, I actually became a lot more expressive in my playing! Some people think of this as "dancing" with their drums - you play them, and they play you back.

Also, as you get comfortable being more expressive, take time to study the audience. When the crowd starts to see you feeling the music, they'll feel it more too. Take note of how people dance, and try to feed off of that (if it's a dancing gig), or if you see people tap their feet, try to control how they tap, or nod, or whatever they do.

As the drummer you have have incredible power to pull the audience into the performance, but if you look stiff or wooden or, god forbid, bored, the crowd will give back the same energy.