By default, the configurable products are indexed as a single record with each configurable product's variants (like colors) indexed as an array of values within the record. (ie: color: [red, blue, green]).
You can turn on the 'Replace default image by matching variation' setting (in the Products tab of the Algolia configuration within the Magento admin):
This means that when a user searches for “blue tshirt”, or refines “blue” (or any other color) using filters, the record will be displayed with a matching image of the blue variant.
In these cases, the price will be displayed as a range (lowest - highest) rather than a specific price for the color.