In library git-core, git has a command that makes all the commits appearing in graphs. For example:
git log --graph --all
It is an other matter to make readable graphs. For that purpose, the following command is helpful to setup a special alias:
git config alias.graph "log --graph --date-order -C -M --pretty=format:\"<%h> %ad [%an] %Cgreen%d%Creset %s\" --all --date=short"
This makes tags and branch names appear in green.
For a command without colors:
git config alias.graph "log --graph --date-order -C -M --pretty=format:\"<%h> %ad [%an] %Cgreen%d%Creset %s\" --all --date=short"
Then this command based on the alias above prints nice-looking graphs.
git graph