You just be yourself, honest and patient, he needs time to regain the strength of his trust, the healing process takes time.
I'm dating a guy who was cheated on by his ex-wife & seems guarded. What is the best way for me to show him love?
Matt Radiance has some good advice.
Just a head's up---rebound relationships aside, it can take up to 2 years for a man to recover from a divorce.
Just be yourself and express love as you feel most comfortable. There's no "best way" here. It will either work or it won't.
You've just got to be who you are so that he isn't dating a pretend version of you, pretence can only be kept up so long because it's draining, then he won't know who he is dating when you have had enough of trying to be someone he may like. You need to let him know who you are right from the get go, regardless of his past. The time is now, the relationship is with you and him.