In the good old days of film, strange colours on the picture was an indication of light reaching the film, that shouldn't be reaching it. It was known as fogging, and usually occured if the camera back wasn't closed properly or if the light seals were faulty. Obviously there is no back as such with a digital camera, but there could be areas where light leakage could occur. Another possibility could be a faulty sensor. I'm not familiar with your model of camera. Does it have adjustable ISO settings? If so does it occur at all settings?
If the camera is at fault it's probably not worth the expense of repairing, as most things these days are unfortunately not 'worth' repairing when you take into account the cost of a repair vs a new item with guarantee.
I'd be interested in seeing your photos if you want click on the envelope next to my name to get my e-mail address