questions on characteristics

I need some direction I have a product that has 5 different sizes small, med etc and then each size has a color however all sizes don't have the same color options but there are alot of color options.

I have the main product and then for characteristics I have

size drop down
color drop down

I want the user to display the size drop down and then the colors for that size to be shown in the color dropdown, no matter what I try I get out of stock message for the variant options that are not available. How do I make it so the second drop down of color will only show the available colors in that size

What is the best way to do this?