WooCommerce Additional Variation Images Plugin
Add any number of images to your variable product variations
The WooCommerce Additional Variation Images Plugin extension allows you to add additional gallery images per variation on variable products within WooCommerce. By default WooCommerce will only swap the main variation image when you select a product variation, not the gallery images below it. This extension allows visitors to your online store to be able to swap different gallery images when they select a product variation. Adding this feature will let visitors see different images of a product variation all in the same colour and style.
Please visit official plugin page for more information