Since you're looking at presentation changes, you probably want to make the changes within the view, rather than within the controller.
ng-style will allow you to assign angularjs class objects which can be changed dynamically.
Here's an example from the documentation:
<input type="button" value="set color" ng-click="myStyle={color:'red'}">
<input type="button" value="set background" ng-click="myStyle={'background-color':'blue'}">
<input type="button" value="clear" ng-click="myStyle={}">
<br/>
<span ng-style="myStyle">Sample Text</span>
<pre>myStyle={{myStyle}}</pre>
Edit:
Here's how you can conditionally apply ng-style based upon function calls within your controller:
<td ng-style="{ background-color: clicked ? 'red' : 'black' }">
And, in your controller function:
var $scope.clicked = false;
var ChangeColor = function($index){ $scope.clicked = true; }
Note also that you can conditionally apply pre-defined style classes with ng-class, as well (see this related question for examples).