Así debe de quedar:
if event.type == pygame.KEYDOWN:
if event.key == pygame.K_LEFT or event.key == pygame.K_a:
message = 'Izaquierda'
print(message)
if event.key == pygame.K_RIGHT or event.key == pygame.K_d:
message = 'Derecha'
print(message)
if event.key == pygame.K_DOWN or event.key == pygame.K_s:
message = 'Abajo'
print(message)
if event.key == pygame.K_UP or event.key == pygame.K_w:
message = 'Arriba'
print(message)
if event.type == pygame.KEYUP:
pass