import bpy

from mathutils import Color, Vector

my_object = bpy.context.active_object.data

vert_list = my_object.vertices
color_map_collection = my_object.vertex_colors

if len(color_map_collection) == 0:
    color_map_collection.new()

color_map = color_map_collection['Col']


torus = bpy.data.objects['Torus']

i = 0
for poly in my_object.polygons:
    for idx in poly.loop_indices:
        loop = my_object.loops[idx]
        v = loop.vertex_index

        selfWC = bpy.context.active_object.matrix_world @ vert_list[v].co
        torusLocalSelfPoint = torus.matrix_world.inverted() @ selfWC
        result,newLocation,newNormal,newIndex = torus.closest_point_on_mesh(torusLocalSelfPoint)
        if result is True:
            finalDirection = (newLocation - selfWC).normalized()
            x = (finalDirection.x + 1) / 2
            y = (finalDirection.y + 1) / 2
            z = (finalDirection.z + 1) / 2
            t = 0
            final = (x,y,z,t)
            color_map.data[i].color = final
        else:
            final = (0.5,0.5,0.5,0)
            color_map.data[i].color = final
        i += 1


# set to vertex paint mode to see the result
bpy.ops.object.mode_set(mode='VERTEX_PAINT')