With such a jagged submission history in this picture, I don’t have any good way to make it tidier. In fact, this is okay, because this submission history truly reflects the entire work process of your warehouse.
If you want to get a clean commit history, I have a suggestion, which is to use the git rebase变基操作，而不是git mergemerge operation when integrating branches. Of course, this suggestion is just to avoid a messy commit history like the one in the picture.
For the use of rebase operations, you can find detailed tutorials in the Progit book.