Can sputum color change color after you cough it up? Ie: go from pink to orange?

May be. If sputum contains fresh blood and inflammatory exudate, the enzymes in the exudate may breakdown red cell and hemoglobin with a resulting change in color. Sputum would probably need to sit at room temperature for a number of hour to see the change. If sputum is collected for lab tests, it should be delivered to the lab asap.