Where are more massive main-sequence stars located on the Hertzsprung-Russell (H-R) diagram relative to less massive ones?

At the upper-left, meaning they are hotter and far more luminous.

The Hertzsprung-Russell (H-R) diagram charts stellar luminosity against temperature (or spectral type), showing the main sequence as a distinct diagonal band. The star's initial mass dictates its precise location along this band while it is fusing hydrogen. More massive main-sequence stars are located toward the upper-left extremity of this band. This placement signifies that they possess the highest surface temperatures and consequently exhibit far greater luminosity, contrasting sharply with lower-mass stars, which reside toward the lower-right end of the sequence as cooler, dimmer objects.