How can I sort deduplicated mySQL data by multiple fields ignoring nulls?

I'm trying to get a list of categories, de-duplicated by siteId in the correct order.

Data looks like this:

categories
=============
categoryId,
siteId,
parentId,
title,
active

Here is my current query:

SELECT
parentTitle,
childTitle,
subChildTitle,
from (
    select      subChild.categoryId as parentCategoryId,
                child.categoryId as childCategoryId,
                parent.categoryId as subChildCategoryId,
                subChild.title as subChildTitle,
                child.title as childTitle,
                parent.title as parentTitle
    from        categories subChild
    left join   categories child on child.categoryId = subChild.parentId 
    left join   categories parent on parent.categoryId = child.parentId 
    where subChild.siteId in (1,2,3)
    and subChild.active = 'Y'
    ) as categories 
group by parentTitle, childTitle, subChildTitle
order by COALESCE(parentTitle, childTitle, subChildTitle);

I get back results like this:

NULL	   NULL	        Appliance	
NULL	   Appliance	Dishwasher	
NULL	   Appliance	Dryer
Appliance  Dishwasher   Not Cleaning Correctly
Appliance  Dryer        Not Cleaning

What i want is this:

NULL	   NULL	        Appliance	
NULL	   Appliance	Dishwasher	
Appliance  Dishwasher   Not Cleaning Correctly
NULL	   Appliance	Dryer
Appliance  Dryer        Not Cleaning

even better would be this: (but i'm fine with it just sorting correct above)

Appliance     NULL        NULL
Appliance     Dishwasher  NULL
Appliance     Dishwasher  Not Cleaning Correctly
Appliance     Dryer       NULL
Appliance     Dryer       Not Cleaning

How about this approach which is just reordering the columns a bit:

SELECT
    parentTitle,
    childTitle,
    subChildTitle
FROM (
    SELECT
        COALESCE(parent.title, child.title, subChild.title) AS parentTitle,
        CASE
            WHEN parent.title IS NULL AND child.title IS NULL THEN NULL
            WHEN parent.title IS NULL THEN subChild.title
            ELSE child.title
		END AS childTitle,
        CASE
            WHEN parent.title IS NOT NULL AND child.title IS NOT NULL THEN subChild.title
		END AS subChildTitle
    FROM categories subChild
    LEFT JOIN categories child on child.categoryId = subChild.parentId 
    LEFT JOIN categories parent on parent.categoryId = child.parentId 
    WHERE subChild.siteId IN (1, 2, 3)
    AND subChild.active = 'Y'
) AS c
GROUP BY parentTitle, childTitle, subChildTitle
ORDER BY parentTitle, childTitle, subChildTitle;

Given the following as source data:

The query returns:

We cannot be sure how your client application is using this data, but it is worth having a read through this blog post, which may help you look at your adjacency list differently.