Organize your WordPress Media Library items in a better way by assigning a category to each item. Media Categories, a WordPress plugin allows you to easily assign categories to your site’s media files using a clean, simple, and searchable category meta box. Then you can use shortcode for displaying media category galleries.
First install and activate the plugin Media Categories then next time while uploading or editing any media file from your WordPress media library you will be noticing a new category section where you can assign categories to media files. No need to bother how many new categories you create for media files because it offers a searchable category box where after typing a few words you get automatic filtered suggestions.
Displaying Category Galleries: This plugin also adds an advantage to WordPresss[gallery]shortcode, it adds category parameter to it. So that you can show media gallery for each category. Values passed to 'category' parameter can either the category slug, or the term_id. Learn more.
For Example:
[gallery category="my-category-slug"] OR [gallery category="12"]