Playing Samba in a drum orchestra involves learning a main groove and breaks. These are different beats that can be different for every instrument in the orchestra. The maestro directs which instruments are playing, when to play breaks and so on. The maestro uses a whistle and hand gestures to direct the music. Samba players can also add flourishes of their own, though these are limited else it all gets a bit cacophonous!
There is music notation and samples (along with lots of other stuff) on the national Rhythms of Resistance site.