Psephology is not very developed in Brazil, but I once read an atlas of Brazilian history which included graphs and maps for all presidential elections since 1945 (the first free and fair election in Brazilian history)
That would be really interesting to delve into and learn about how political coalitions have evolved there.
Actually, the book was old and only went back to 1989; there were five direct presidential elections during the time period (with a hiatus due to the military dictatorship between 1964-1985)