I notice that when I am typing my left hand is paler in color when compared to the right. Sometimes I feel a slight trembling in that hand as well.?

Need further tests. Sound like either vascular (blood flow) or nerve related problem. Carpal tunnel syndrome can present this way although you did not mention numbness, tingling or pain. It could also be constriction of blood vessel in the hand that makes the color change. Women are more prone to this condition. You will need full clinical eval and xray, emg, blood test, and possibly arterial doppler.
Many causes. There are some serious conditions such as thorac outlet syndrome which could explain this but it is difficult to assess in this format and should be evaluated in person.