What I had in mind is that the engine Room would be pretty cramped compared to the later generations of Starship, Anyway as you can see there's a wall console to the left and behind the blast door is the Warp Core, To the left of that in the alcove there is the Chief Engineer's office where he keeps track of everything related to the Engineering systems, The Engine Room is located on Deck 3 with the Deuterium and Antimatter fed from the central area of Deck 3 via their respective storage tanks. The Tubes you see to the right are what feeds the Matter and Antimatter to the Warp Core with blue and red denoting Matter and Antimatter respectively, Nothing here is finalized so things will be subject to Change.
Edit as of 10/15/17 at 1100 Hours: I forgot to add the principled shader to the Matter tube so I decided to make a few changes that I would feel makes the Engine Room feel like it's in the bowels of the ship such as changing the main lighting from white to dull blue and giving the Engineering Console similar lighting that was seen on the TOS Bridge.
Edit as of 10/15/17 at 1719 Hours: Added the tank like structures seen from TOS to pad out the room and darkened the windows on the blast door at CaptnObviousFTW's recommendation as we both had the idea that the windows would polarize to prevent the engineers from going blind when the Warp Core is active.
Star Trek and all related Elements (c) Gene Roddenberry, Paramount Pictures and CBS Studios
Star Trek Castaways and all related elements (c) SpiderTrekfan616,CaptnObviousFTW and The6thNightguard