Hi Vanita,
as far as I know Articulate only allows you to change the colors of their built in "icons". Other formats - like illustrations or inserted .svg files - are not supported.
If you want to change the color of an illustration to match your corporate colors (or any other color) you will need to do so in a software like illustrator, gimp, photoshop ... and then import it into articulate again.
Another thing you can try is changing the color in powerpoint and copying back into your articulate storyline slide. Powerpoint supports the feature you describe above - as long as the file is vector based (such as .svg).
hope that help :)