The fact that the leaves are green suggests it is not getting enough light.
The basic color of the plant is red, which is masked by green chlorophyll. In brighter light, the plant doesn't need to produce so much chlorophyll for photosynthesis and the red color is visible.
Also, if you think it doesn't look very nice with the shoots growing horizontally, you could use each set of leaves as a cutting and get four plants instead of one. Just cut the old stem into segments and plant each one with the stem horizontal in the ground and the leaves vertical. Water the pots before you plant the cuttings and do not water them again until they start to grow, or they may rot and die.