I am not sure what you mean by visible light - note that how the light itself appears to the camera is not the "Direct" light (Direct light is the light from the light source falling onto a surface in the scene, while indirect light is after that light bounces off a surface). You can control how the light source itself looks simply by having two light sources - the one that you have for casting light into the scene, just uncheck visible to camera, then duplicate it, turn emit light, and enable visible to camera, then make it look how you want the light source to seem in camera. That is, unless you really mean Direct light and not how the light source looks to the camera :)
