If/Else statement in Jquery

JSFiddle

I have a navigation filter that when clicked, each project will be highlighted depending on what category they are under. I would like that when clicking the #all-btn, all the items will be highlighted their respective color. Right now, they are set to highlight black, but I would like to change that. For example,

Graphic design will be green, Web design will be red, Flat design will be blue.

I would think that an if/then statement in the jQuery could achieve this but not sure how to frame it up. I.E.

if (the item has class graphic) { 
    $("#projects").find("li.graphic").toggleClass("highlight-graphic");
} 
else if (item has class web) {
    $("#projects").find("li.web").toggleClass("highlight-web");
} 
else {
    $("#projects").find("li.flat").toggleClass("highlight-flat");
}

What would be a good way to set this up, and would this work?