丧 here is read as the neutral 5th-tone sang (not the formal sàng "to mourn / to lose") — and
着 is the durative-aspect particle zhe, not zháo. The literal sense is "face arranged as if at a funeral (
哭丧)" — wearing a mourner's expression even when nothing tragic has happened. Negative tone, often used impatiently:
别哭丧着脸了！ "Stop pulling that face!"
