magento-test/app/code/Magento/SwatchesGraphQl/etc/graphql/di.xml

<?xml version="1.0"?>
<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <type name="Magento\CatalogGraphQl\Model\Resolver\Layer\DataProvider\Filters">
        <plugin name="add_swatch_data_to_filters" type="Magento\SwatchesGraphQl\Plugin\Filters\DataProviderPlugin"/>
    </type>
    <type name="Magento\CatalogGraphQl\Model\LayerFilterItemTypeResolverComposite">
        <arguments>
            <argument name="typeResolvers" xsi:type="array">
                <item name="swatch_layer_filter_item" xsi:type="object">Magento\SwatchesGraphQl\Model\Resolver\SwatchLayerFilterItemResolver</item>
            </argument>
        </arguments>
    </type>
</config>