I doubt it will be, but it's more than a yard, it may be easier to call a redi-mix company to deliver it when you've got the forms and rebar/wire in place. (Some places will deliver a yard, others require a two-yard minimum to deliver.)
Here's a way to figure out whether your pad will require more than a yard (it will depend on the depth you make the slab):
Length x Width equals total square feet. One square yard of concrete will spread 81 square feet at a 4 in. depth. One square yard of concrete will spread 54 square feet at a 6 in. depth.
3 foot concrete sidewalk x 40 feet long = 120 square feet.
120 square feet divided by 81 = 1.18 yards of concrete at a 4 in. depth.