For the sake of clarity, let's assume an 8th level Magus with a BAB of +6/+1
Option 1) Casting Shocking Grasp with Spellstrike
Use standard action
Cast Shocking Grasp
Per casting rules, gain a free touch attack
Using Spellstrike make a weapon attack at +6 against target.
Option 2) Spell Combat
Use a Full Round Action
Cast Shield.
Make weapon attack at +4 (-2 penalty for using Spell Combat)
Make weapon attack at -1 (-2 penalty for using Spell Combat)
Scott
Option 3) Spell Combat with Spellstrike
Use a Full Round Action
Cast Shocking Grasp
Per casting rules gain a free touch attack
Using Spellstrike make a weapon attack at +4 against target (-2 penalty for using Spell Combat)
Make weapon attack at +4 (-2 penalty for using Spell Combat)
Make weapon attack at -1 (-2 penalty for using Spell Combat)
Option 3) Spell Combat with Spellstrike
Use a Full Round Action
Cast Shocking Grasp
Per casting rules gain a free touch attack
Using Spellstrike make a weapon attack at +4 against target (-2 penalty for using Spell Combat)
Make weapon attack at +4 (-2 penalty for using Spell Combat)
Make weapon attack at -1 (-2 penalty for using Spell Combat)