$products = new WP_Query( array(
'post_type' => array('product'),
'post_status' => 'publish',
'posts_per_page' => -1,
'meta_query' => array( array(
'key' => '_visibility',
'value' => array('catalog', 'visible'),
'compare' => 'IN',
) ),
'tax_query' => array( array(
'taxonomy' => 'pa_color',
'field' => 'slug',
'terms' => array('blue', 'red', 'green'),
'operator' => 'IN',
) )
) );