The reason the fluid is low could be a leak even though you have already checked. The orange color ties--if fluid gets out, water can get in.
I don't know how long you have owned your X but the fluid could have been changed and could have been that or close to that color out of the bottle--just not properly filled. Is it translucent? Do you know whether it has been previously changed?
That said, If I couldn't find a leak, and I didn't know it it has been changed my first effort would be to extract all of old fluid out, refill it with an appropriate fluid that is a contrasting color. I would drive it a few miles and check the color. If it has changed I would remove it and refill it again. I would repeat that process until I was OK with the color. .
Going this route might be ignoring logic but it would correct the problem of low and discolored fluid. I would check the fluid level in 100 miles and see what it looked like and see if it was down see where I am.