You could add in your view a hidden field with the content type and either rewrite the results of each field and add wrapper to each field using the available value (content type) or theme the specific view and add a class to the row wrapper based on content type (which still is passed to your view as a field).
In case you need to add a class to the row:
For D7 in Advanced settings you can check the theme: information and create template file for your rows based on the suggestions of the informations.
If you work on D8 you can create a template file check (https://api.drupal.org/api/drupal/core%21modules%21views%21templates%21views-view-grid.html.twig/8.0.x) where you have all the views data so as you can add all a wrapper to each row.
Whatever version you use have a look at theme hook suggestions D7 -
https://www.drupal.org/docs/7/theming/template-theme-hook-suggestions and D8 - https://api.drupal.org/api/drupal/core%21modules%21views%21views.theme.inc/group/views_templates/8.2.x in order to make sure how to name your template and which template you really need.
If you just need to add a class to a field:
In your views put your content type field at the top of the fields and add a new field or edit an existing one. Go to REWRITE RESULTS and select Rewrite the output of this field. Below of this you will find a list of all the replacement patterns which you can use to create your own markup with all the details you need.