GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
InstallGlobalFunction(SylowSubgroupOfCatOneGroup_alt,
function(C,p)
local
G,P,Gens,s,t,sp,tp,
Num,i,k;
s:=C!.sourceMap;
t:=C!.targetMap;
G:=Source(s);
P:=SylowSubgroup(Image(s,G),p);
k:=1;
Num:=Factors(Order(G));
for i in Num do
if i=p then
k:=k*p;
fi;
od;
while Order(P)<k do
P:=SylowSubgroup(Normalizer(G,P),p);
od;
Gens:=GeneratorsOfGroup(P);
sp:=GroupHomomorphismByImages(P,P,Gens,List(Gens,x->Image(s,x)));
tp:=GroupHomomorphismByImages(P,P,
Gens,List(Gens,x->Image(t,x)));
return Objectify(HapCatOneGroup, rec(
sourceMap:=sp,
targetMap:=tp,
));
end);