Air Carrier pilot taxiing at night in IAH reported turning at the wrong spot due to lack of painted taxi lanes on the pavement.

Narrative

IAH at night and positioned at Spot XX on North Ground frequency 118.57. North Ground Control issued clearance to Runway 33L via - NB left on ND right on NC hold short of NR call Ground on 121.7. Ground Control on 121.7 subsequently asked us to follow an aircraft on taxiway WB (near WW) and follow Aircraft Y on WB to Runway 33L.I began to make a left turn on NE to join WB at WW as there are no taxi lanes on the ground from NC to WB. Ground Control asked why we were turning left. We attempted to explain that there was no defined path for his instruction. At night with no painted center lines to follow; (and as typical for the Aircraft X a nose taxi light that is only marginally better than a candle) it appeared that we may depart the hard surface and end up in the grass or dirt. It was only when I turned on my landing and runway turnoff lights that I could see there was hard surface between NC and WB.There are no painted taxi lines between these taxiways. I rarely allow the nose wheel to depart a centerline unless I am maneuvering in a holding pad. The only guarantee that you are not encroaching on other aircraft or obstacles is to ensure that your aircraft is over a center line. There needs to be painted taxi lanes between these two taxiways if there is going to be a clearance from one to the other.