I want to know if there is possible to show in a different style the posts (cb activity wall) like in a masonry way. I mean, there is a templates plugin or something to change that presentation?
You can create new templates for CB Activity by making a copy of the default template folder, renaming it, deleting everything in it that you don't intend on changing, then selecting your template within CB Activity > Parameters > General. See the below for default template location.
/components/com_comprofiler/plugin/user/plug_cbactivity/templates/default
If all you want to do is override the CSS of the default template it's even easier. Simply create a new folder (e.g. "custom") in the below folder.
/components/com_comprofiler/plugin/user/plug_cbactivity/templates
Next create an override.css file and place all your custom CSS there.
I want to show activity posts more modern like a pinterest or something like that. Is there any option?
It's possible, but you'll have to write all the styling code your self.