Volvo S40/V40 jacking points and using axle stands
According to the Haynes manual for the S40 and V40:
To raise the front of the car, place the jack head underneath the braced underbody section behind the lower arm rear mounting. To raise the rear of the car, the jack head should be positioned under the outer end of the lower suspension arm, directly beneath the strut mounting. Always use a flat piece of wood on the jack head, to prevent damage.
When the car's been raised to the required height, support it on an axle stand placed under one of the vehicle jack location points on the sill. To protect the sill edge, use a block of wood with a slot cut in it, on the head of the axle stand.
...The lifting points are marked by two notches on the sill edge – models with plastic sill covers will have an arrow marking to indicate the jacking points.
This video on Youtube will show you how to identify the jacking points: