(J − H, [3.6]−4.5]) color-color diagram showing the locations of both high-confidence members of the W40 region (large symbols) and candidate members with Gaia eDR3 parallaxes between 1 and 3 mas (small symbols). Filled circles correspond to stars projected within the boundaries of the central cluster. The solid line is the predicted locus of the colors of unreddened stars with effective temperatures between 30 000 K and 2500 K, according to the MESA 1 Myr isochrone (which is virtually undistinguishable from the locus corresponding to other isochrones in the same temperature range). The dotted line is the reddening vector, with a length corresponding to A_V = 20 mag, having its origin at the unreddened colors of the coolest stars that we consider in this work.