Technically No you can't use Slope
You should use (Elevation Raster) instead of (Slope raster)
Because (Elevation Raster) represents the surface but (Slope Raster) is representing the most frequently run on an elevation dataset.
So the (Slope) is just a characteristic of the elevation which it can be computed using
slope_degrees = ATAN ( √ ([dz/dx]2 + [dz/dy]2) ) * 57.29578
According to ESRI, Raster Surface tools in ArcGIS considers that Slope is one of the surface tools.
--How the inverting surface works:--
In general, it's mathematical approach to be done.
(([elevgrd] - Z_Max) * -1) + Z_Min
Where: [elevgrd] is the name of the input surface, Z_Max is the surface maximum and Z_Min is the surface minimum.
In your case (Wrong):
Because you used the slope values not the elevation values
[elevgrd] = [slope_map]
Z_Max = The maximum slope from your raster = 40
Z_Min = The minumum slope from your raster = 1
As you can see from both pictures how the max and min values are different (Elevation VS Slope)