Add inline style to get_the_category_list

get_the_category_list() does not really have any filters to achieve what you want. You will currently need PHP like preg_replace() to alter the anchor tags. The big issue would be to get the current link’s term object, which in my opinion would turn it into a quite messy procedure.

You could however write your own function to achieve the same

function wpse_219554_term_list()
{
    $post = get_post();

    $separator=" ";
    $output    = [];

    $post_categories = get_the_category( $post->ID );
    if ( $post_categories ) {
        foreach( $post_categories as $post_category ) {
            $category_color = get_field( 'category_color', $post_category );
            $output[] = '<li class="meta-category">
                             <a style="color:' . $category_color . ';" href="' . esc_url( get_category_link( $post_category ) ) . '" alt="' . esc_attr( sprintf( __( 'View all posts in %s', 'mytheme' ), $post_category->name ) ) . '"> 
                                 ' . esc_html( $post_category->name ) . '
                             </a>
                        </li>';
        }

        if ( $output )
            echo implode( $separator, $output );
    }
}

EDIT 08 March 2016

The source code of get_the_category_link() is quite messy and quite repetitive, so I have submitted a trac ticket for a possible clean-up and micro optimization of the code.

I have also suggested a new filter, the_category_list_links, which can be used to individually filter category links according to category. If this gets accepted into core, we can use the filter to filter the links as per OP needs, something like this will work then

add_filter( 'the_category_list_links', function ( $the_link_list, $category, $cat_parents )
{
    $category_color = get_field( 'category_color', $category );
    if ( !$category_color )
        return $the_link_list;

    $the_link_list = str_replace( '<a', '<a style="color:' . $category_color . '"', $the_link_list );

    return $the_link_list;
}, 10, 3 );

You can read and contribute to the current trac ticket #36171, and please, feel free to to propose changes so we can get this into the next major release